Wheelchair

ABSTRACT

The present disclosure may relate to a wheelchair that includes a first centerless wheel assembly including a drive roller guide assembly and three other roller guides, and a first drive mechanism coupled to the first drive roller guide assembly to drive the first centerless wheel assembly. The wheelchair may also include a second centerless wheel assembly including a drive roller guide assembly and three additional roller guides, and a second drive mechanism coupled to the second drive roller guide assembly to drive the second centerless wheel assembly.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/179,357, filed on May 4, 2015, which is incorporated herein byreference in its entirety.

FIELD

The embodiments discussed in the present disclosure relate to awheelchair.

BACKGROUND

Some wheels have spokes made of tensioned, adjustable metal wires, orsome other connecting body between the edge and the middle of the wheel.The spokes may connect a rim of a particular wheel to a hub of theparticular wheel and may help support an applied load. Wheels withtensioned spokes may be used in bicycles, wheelchairs, motorcycles,automobiles, and other vehicles.

The subject matter claimed in the present disclosure is not limited toembodiments that solve any disadvantages or that operate only inenvironments such as those described above. Rather, this background isonly provided to illustrate one example technology area where someembodiments described may be practiced.

SUMMARY

One or more embodiments of the present disclosure may include awheelchair that includes a first centerless wheel assembly including adrive roller guide assembly and three other roller guides, and a firstdrive mechanism coupled to the first drive roller guide assembly todrive the first centerless wheel assembly. The wheelchair may alsoinclude a second centerless wheel assembly including a drive rollerguide assembly and three additional roller guides, and a second drivemechanism coupled to the second drive roller guide assembly to drive thesecond centerless wheel assembly.

The object and advantages of the present disclosure will be realized andachieved at least by the elements, features, and combinationsparticularly pointed out in the claims.

It is to be understood that both the foregoing general description andthe following detailed description are given as examples and areexplanatory and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be described and explained with additionalspecificity and detail through the use of the accompanying drawings inwhich:

FIG. 1 illustrates a diagram representing an example centerless wheelassembly;

FIG. 2 illustrates a diagram representing an example centerless wheelassembly with slots;

FIG. 3 illustrates a diagram representing an example centerless wheelassembly with an example rim-braking mechanism;

FIG. 4 illustrates a cutaway view of an example centerless wheelassembly;

FIG. 5 illustrates a diagram representing an example centerless wheelassembly;

FIG. 6A illustrates a cross-sectional view of an example centerlesswheel assembly;

FIG. 6B illustrates a cross-sectional view of another example centerlesswheel assembly;

FIG. 6C illustrates a cross-sectional view of a portion of anotherexample centerless wheel assembly;

FIG. 7 illustrates a diagram of another example centerless wheelassembly that may be driven;

FIG. 8A illustrates a top cutaway view of another example centerlesswheel assembly;

FIG. 8B illustrates a diagram of the centerless wheel assembly of FIG.8A;

FIG. 9 illustrates a diagram of an example centerless wheel assemblythat may include an exterior input driver that may drive a tire;

FIG. 10A illustrates a top cutaway view of a dual-driving centerlesswheel assembly;

FIG. 10B illustrates a diagram of the dual-driving centerless wheelassembly of FIG. 10A; and

FIG. 11 illustrates a cutaway view of an example centerless wheelassembly that may include multiple roller guide assemblies;

FIG. 12A illustrates a front view of an example wheelchair;

FIG. 12B illustrates a side view of the example wheelchair of FIG. 12A;

FIG. 13 illustrates a side cutaway view of an example wheel assembly ofa wheelchair;

FIG. 14A illustrates a front view of an example wheel assembly of awheelchair in a first position;

FIG. 14B illustrates a front view of an example wheel assembly of awheelchair in a second position;

FIG. 14C illustrates a front view of an example wheel assembly of awheelchair in a third position;

FIG. 14D illustrates a front view of an example wheelchair;

FIG. 15A illustrates an example wheel assembly and associated drivemechanism of a wheelchair;

FIG. 15B illustrates the example wheel assembly and associated drivemechanism of a wheelchair of FIG. 15A;

FIG. 16 illustrates an exploded view of an example drive mechanism of awheelchair;

FIG. 17 illustrates an example wheel assembly and associated drivemechanism of a wheelchair;

FIG. 18 illustrates an example wheel assembly and associated drivemechanism of a wheelchair;

FIG. 19 illustrates an exploded view of an example wheel assembly andassociated drive mechanism of a wheelchair;

FIG. 20 illustrates an exploded view of an example drive mechanism;

FIG. 21 illustrates an example wheel assembly;

FIG. 22 illustrates an example wheel assembly with an example hand rail;

FIGS. 23A, 23B, and 23C illustrate cutaway views of example hand rails;

FIG. 24 illustrates an example wheel assembly with an example hand railwith various sensors;

FIG. 25A illustrates an example of a centerless wheel assembly able toinvoke a corrective action;

FIG. 25B illustrates another example of a centerless wheel assembly ableto invoke a corrective action;

FIG. 26 illustrates a flow chart of an example method of addressingslippage.

DESCRIPTION OF EMBODIMENTS

The present disclosure relates to a centerless wheel assembly. In someembodiments, such an assembly may include a tire configured to contactthe ground and a centerless rim coupled to the tire such that rotationof the centerless rim also causes the tire to rotate. The centerless rimmay have a void of material in the middle of the rim, although a pointreferred to as the “center” may be referenced for ease in discussingoperation, relative positions, etc. of the present disclosure. In someembodiments, the centerless wheel assembly may also include a pair ofgenerally circular exoskeleton plates located proximate the centerlessrim and shaped such that the middle of the centerless wheel may begenerally void of material. The exoskeleton plates may support one ormore roller guide assemblies. The roller guide assemblies may include abridging shaft that spans between the exoskeleton plates and functionsas an axle for a roller guide of the roller guide assembly (e.g., bybeing fixed to each of the exoskeleton plates so the roller guide mayrotate around the bridging shaft). The roller guide may be shaped andconfigured to roll along the centerless rim, either continually duringuse or under protective circumstances (e.g., when the centerless wheelassembly hits a pothole). In some embodiments, one or more of the rollerguides may operate based on static friction between the roller guide andthe centerless rim. For example, as the roller guide rotates, therotation may in turn cause the centerless rim to rotate about the rollerguide, thus, effectively rotating the tire about an axis through thecenter point of the centerless rim. In some embodiments, one or moreroller guides may be caused to rotate via a manual drive (e.g., bicyclepedals) or through an engine or motor (e.g., an electric motor).

Some embodiments of centerless wheel assemblies described in the presentdisclosure may have one or more of the following advantages: simplicity,low weight, low cost, low rotational friction, stable thermalproperties, aerodynamic, and improved gear efficiencies. Centerlesswheel assemblies in accordance with one or more embodiments may be usedon any number of vehicles or transportation devices, including, forexample, vehicles with any number of wheels, self-propelled vehicles,manually powered vehicles, motorized vehicles, mobility-aiding vehicles,cars, wheelchairs, etc. The centerless wheel assembly may be used totransport people and/or goods.

In some embodiments, various roller guide assemblies may be referenced.Any roller guide provided with a motive force (e.g., from a motor, anengine, bike pedals, lever arms, etc.) may be referred to as a driveroller guide or a friction roller guide. In these and other embodiments,a drive roller guide may be shaped, positioned, and/or configured todrive a wheel. Additionally or alternatively, a roller guide that maynot be provided with a motive force may be referred to as an idlerroller guide or a limiter roller guide. In these and other embodiments,an idler roller guide may be shaped, positioned, and/or configured toroll along a rim of a wheel. In these and other embodiments, a limiterroller guide may be shaped, positioned, and/or configured to limit thelimiter roller guide and/or other roller guides from coming off of therim of the wheel assembly.

Some embodiments of the present disclosure relate to a wheelchair thatmay use centerless wheel assemblies as at least one of the wheels of awheelchair. The wheelchair may also include a payload region (e.g.,where a user of the wheelchair would ride) and a drive mechanism todrive at least one of the wheel assemblies. The drive mechanism mayinclude one or more manually driving features (e.g., by hand-rails, or alever mechanism), one or more powered driving features (e.g., anelectric motor), or any combinations thereof.

Embodiments of the present disclosure are explained with reference tothe accompanying drawings.

FIG. 1 illustrates a diagram of a wheel assembly 10, according to someembodiments. In some embodiments, the wheel assembly 10 may include anexoskeleton assembly 12, which may include one or more of the following:a first roller guide assembly 14, a second roller guide assembly 16, acenterless rim 18, a first exoskeleton plate 13, a second exoskeletonplate opposite the first exoskeleton plate 13 (not illustrated), a firstlimiter 28, a second limiter 30, and a first expansion bushing 64. Theexoskeleton assembly 12 may be coupled to a tire 32. For example, thecenterless rim 18 may be directly coupled to the tire 32 such that asthe rim 18 is rotated, the tire 32 also rotates.

In some embodiments, the first roller guide assembly 14 may include afirst bridging shaft 15 spanning between the first exoskeleton plate 13and the second exoskeleton plate, and the first bridging shaft 15 mayfunction as an axle for the first roller guide 24. The first rollerguide 24 may roll along the rim 18. Additionally or alternatively, thesecond roller guide assembly 16 may include a second bridging shaft 17that may be similar or identical to the first bridging shaft 15 of thefirst roller guide assembly 14.

In some embodiments, the first roller guide 24 may be made of anymaterial that is able to roll along the centerless rim 18 due to staticfriction. For example, the material may be selected to provide wearresistance and sufficient friction to drive or otherwise roll along thecenterless rim 18. For example, the first roller guide 24 (and anyroller guide of the present disclosure) may be made of a polymer, suchas polyurethane, poly vinyl chloride (PVC), acetal (homopolymer), acetal(copolymer), nylon 66, nylon 66 (with 30% glass), phenolic (glassfilled), polyetherimide, polyetheresulphone, polyimide, polyphenylenenesulfide, polysulfone, polytetrafluoroethylene (PTFE) (e.g., Teflon®),polyethylene (including ultra-high molecular weight (UHMW)), carbonfiber, aluminum, titanium, polyoxymethylene (e.g., Delrin®), etc.

In some embodiments, the first roller guide assembly 14 may include oneor more first bearings 20 and/or the second roller guide assembly 16 mayinclude one or more second bearings 22. In some embodiments, the firstbearings 20 may be rotatably disposed within the first roller guideassembly 14 and/or the second bearings 22 may be rotatably disposedwithin the second roller guide assembly 16. For example, the firstbearings 20 may facilitate or otherwise make easier or more efficientthe rotation of the first roller guide 24 about the first bridging shaft15.

In some embodiments, the first and second bridging shafts 15, 17 may becoupled with the first exoskeleton plate 13 and the second exoskeletonplate. In some embodiments, the first exoskeleton plate 13 and thesecond exoskeleton plate may be spaced apart, and the first and secondbridging shafts 15, 17 may each form a bridge across a gap between thefirst exoskeleton plate 13 and the second exoskeleton plate. Forexample, any of the first roller guide assembly 14, the second rollerguide assembly 16, the first limiter 28 and the second limiter 30 may bedisposed within the gap between the first exoskeleton plate 13 and thesecond exoskeleton plate. In some embodiments, the first and secondexoskeleton plates may correspond to right-hand and left-handexoskeleton plates. In some embodiments, the first bearings 20 and/orthe second bearings 22 may be disposed within a circumference of thecenterless rim 18.

In some embodiments, an angle between the first bearings 20 and thesecond bearings 22 and/or the first roller guide assembly 14 and thesecond roller guide assembly 16 may be between approximately ten degrees(10°) and one hundred and forty degrees) (140°) with respect to a center11 of the rim 18. In some embodiments, the angle may be between zerodegrees (0°) and three hundred and sixty degrees (360°), or may beplaced at any of a variety of locations around the wheel assembly 10. Inthese and other embodiments, the location of the first roller guideassembly 14 and the second roller guide assembly 16 may be symmetrical.Stated another way, if the wheel assembly 10 were analogized to a clockface, the angle between the first roller guide assembly 16 and thesecond roller guide assembly 14 may distribute forces acting on thewheel assembly 10 at a six o'clock position. For example, if the firstroller guide assembly 14 and the second roller guide assembly 16 werelocated at a five o'clock and seven o'clock positions, the forces wouldbe distributed to be balanced at the six o'clock position where thewheel assembly 10 contacts the ground. The angle between the firstroller guide assembly 14 and the second roller guide assembly 16 mayalso reduce rotational friction and/or facilitate withstanding ofextreme G-forces, such as, for example, 5 g, by the centerless rim 18when the wheel assembly 10 is dropped from a height and/or experiencesan external load.

In some embodiments, the first roller guide 24 and/or the second rollerguide 26 may be configured to include a shape or profile that matches acorresponding shape or profile of the rim 18. For example, the rim 18may be completely void of material in the middle of the centerless rim18 and the first roller guide 24 and/or the second roller guide 26 maybe disposed within the void of material. In some embodiments, the firstroller guide 24 and/or the second roller guide 26 may contact the rim18. In some embodiments, the first roller guide 24 and/or the secondroller guide 26 may be configured to act upon and guide the rim 18 asthe rim 18 rotates around the first roller guide assembly 14 and/or thesecond roller guide assembly 16. In some embodiments, the first andsecond roller guides 24, 26 may be coupled with the first bearings 20and the second bearings 22, respectively, and may be rotatably disposedabout the first and second bridging shafts 15, 17, respectively.

In some embodiments, each of the first exoskeleton plate 13 and thesecond exoskeleton plate may have a generally circular configuration,and may include a void in material through a central region.Additionally or alternatively, the exoskeleton plates may be a solidsheet of material (including square or rectangular sheets of material),tubular, or any other shape or form such that the roller guides aresupported proximate the centerless rim. In some embodiments, each of thefirst and second exoskeleton plates may have a lip about an outercircumference or outer edge. In some embodiments, the rim 18 may beretained between the first and second exoskeleton plates as the rim 18rotates about the first and/or second roller guide assemblies 14, 16. Insome embodiments, the exoskeleton plate 13 may span the rim and functionas both the first exoskeleton plate 13 and the second exoskeleton plates(an example of such an embodiment is illustrated in FIG. 6C). In theseand other embodiments, the exoskeleton plate 13 may be constructed of asingle piece of material that supports both ends of a bridging shaft.

In some instances, such as when a pothole, debris, or another roadwayimperfection is struck by the wheel assembly 10, one or more of thefollowing may be subject to side-loading and/or forces: the wheelassembly 10, the exoskeleton assembly 12, and the rim 18. In someembodiments, when the side-loading and/or the forces are experienced,the rim 18 may remain in a constant or near constant state of alignmentwith respect to the exoskeleton assembly 12 such that oscillation and/orrotational friction is reduced.

In some embodiments, the rim 18 may be spaced apart from one or more ofthe following components by a distance: the first exoskeleton plate 13,the second exoskeleton plate, the first limiter 28, the second limiter30, and/or the first expansion bushing 64. The distance may include anyamount, for example, one, two, three, four, five, ten, fifteen, etc.thousandths of an inch. Further, the distances between the rim 18 anddifferent components may be different.

In some embodiments, in response to the wheel assembly 10 becomingairborne, the rim 18 may descend such that the rim 18 may contact and/ormay no longer be spaced apart from one or more of the roller guideassemblies and/or one or more of the limiters (e.g., the first rollerguide 14, the second roller guide 16, the first limiter 28, and/or thesecond limiter 30). In these and other embodiments, the first limiter 28and/or the second limiter 30 may prevent the rim 18 from becomingseparated and/or dislodged from the exoskeleton assembly 12 in responseto, for example, the wheel assembly 10 becoming airborne. For example,as the wheel assembly 10 becomes airborne such that the ground no longerexerts a force on the wheel assembly 10, a spring force may cause thefirst and/or the second limiter 28, 30 to contact the rim 18.Additionally or alternatively, as the wheel assembly 10 becomesairborne, gravity may cause the rim 18 to drop, but only far enough tocontact one of the limiters, thus, only changing position as far as thegap between the rim 18 and the limiters.

In some embodiments, one or more of the limiters may be configured tocause the first roller assembly 14 to maintain contact with the rim 18.For example, a limiter may be disposed upon a spring loaded lever armsuch that as the position of the rim 18 is changed relative to the firstand second exoskeleton plates (e.g., due to irregularities in thecenterless rim 18 or the tire 32), the limiter on the lever arm mayengage the rim 18 so that the rim 18 maintains contact with the firstroller guide 14. As another example, the limiter may be positioned veryclose to the rim 18 such that if the rim 18 moves such that the rim 18may no longer be in contact with the first roller guide 14, the rim 18may contact the limiter and be maintained in contact with the firstroller guide 14. In some embodiments, the limiters may include a rollerthat may be similarly shaped to engage with the rim 18. In these andother embodiments, the limiters may include a roller guide that may bedriven.

In some embodiments, the rim 18 and/or the tire 32 may be non-uniformlycircular. For example, the rim 18 and/or the wheel may expand orcontract or otherwise change shape due to variations in temperature orother weather conditions, or may be non-uniformly circular due tomanufacturing errors, imperfections that may result in dynamic run out,or eccentricity caused by damage in various states of utilization.Expansion or contraction of the rim 18 may cause the rim 18 and/or thewheel assembly 10 to take on an irregular or eccentric shape. In someembodiments, in response to the rim 18 being subjected to an external orinternal load and/or in response to the rim 18 expanding or contracting,the wheel assembly 10 may operate in a reasonably predictable mannerwith respect to rotational friction, tracking, alignment, and brakingperformance due to one or more of the following: the first limiter 28,the second limiter 30, and the first expansion bushing 64. For example,the first expansion bushing 64 may allow contraction or expansion of thefirst exoskeleton plate 13 and/or the second exoskeleton plate whilestill maintaining a desired shape or maintaining one or more of theroller guide assemblies relative to the centerless rim 18. For example,the expansion busing 64 may include rubber or other compressiblematerial disposed in a gap of the first exoskeleton plate 13 and/or thesecond exoskeleton plate such that a certain amount of change in shapeor size may occur in a controlled manner. As another example, theexpansion bushing 64 may include a metal material at a gap in the firstexoskeleton plate 13 and/or the second exoskeleton plate such that asthe exoskeleton plates experience variations in size a targetorientation between the first roller guide 14 and the rim 18 may bemaintained. As another example, the first limiter 28 and/or the secondlimiter 30 may provide multiple points of contact or potential contactwith the rim 18 such that even in a non-uniformly circular shape, one ormore of the roller guides maintains contact with the rim. As anotherexample, the first limiter 28 and/or the second limiter 30 may be springloaded such that as the rim 18 or another element of the wheel assembly10 departs from a uniformly circular shape, that departure iscompensated for by the flexibility in movement provided by the springforce while also maintaining contact with the rim 18.

In some embodiments, the expansion bushing 64 may be include in place ofthe first and/or the second limiters 28, 30. Additionally oralternatively, the expansion bushing 64 may be included in addition tothe first and/or the second limiters 28, 30.

In some embodiments, the first and/or the second limiter 28, 30 may besized and/or disposed such that during normal operation, the rim 18 maynot be in physical contact with the first and/or the second limiter 28,30. In these and other embodiments, when the rim 18 and/or the tire 32departs from a generally uniformly circular shape (e.g., due to hittinga pothole), at least one of the first and/or the second limiter 28, 30may be in physical contact with the rim 18.

In some embodiments, the first limiter 28 and/or the second limiter 30may prevent damage to the rim 18 when the wheel assembly 10 is exposedto harsh environments, impacts, uneven road surfaces, drop offs, forces,and other conditions that may otherwise cause damage to the rim 18. Inthese and other embodiments, the first limiter 28 and/or the secondlimiters 30 may be spaced apart from an interior circumference or edgeof the rim 18 by a gap. For example, there may be a gap of approximatelyat least one, two, three, four, five, ten, fifteen, etc. thousandths ofan inch. The gap may be reduced or eliminated in response to theexoskeleton assembly 12 experiencing a drop from an elevation and/or acompression due to a great force or impact such as, for example, anabrupt or sudden stop. The first limiter 28 and/or the second limiter 30may contact the rim 18 in response to the drop and/or the compression,which may mitigate effects of the drop and/or the compression.

In some embodiments, the wheel assembly 10 may include any number ofroller guide assemblies disposed at various positions with respect tothe exoskeleton assembly 12, which may be identical or similar to thefirst and second roller guide assemblies 20, 22 and/or the first andsecond limiters 28, 30. For example, in some embodiments the exoskeletonassembly 12 may include at least three roller guides or limiters. Insome embodiments, the first limiter 28 and/or the second limiter 30 mayinclude a roller guide assembly similar or identical to the first rollerguide assembly 14. Additionally or alternatively, the first limiter 28and/or the second limiter 30 may include a bridging shaft, but one ormore other components of the first roller guide assembly 14 may beabsent.

In some embodiments, the wheel assembly 10 may include at least fourroller guides (e.g., the first and second roller guide assemblies 20, 22and the first and second limiters 28, 30). Such an embodiment of fourroller guides may be advantageous over three roller guides for a varietyof reasons. For example, in a number of experiments it has been foundthat the roller guides are more likely to derail or otherwise becomedisconnected from the rim when three roller guides are used instead offour roller guides. Such a result has particularly been seen inembodiments in which the wheels are side by side, such as a wheelchair,automobile, skateboard, etc.

In some embodiments, the wheel assembly 10 may include the limiter 28disposed on a lever arm 33. In these and other embodiments, the leverarm 33 may operate as a quick release mechanism to allow the centerlessrim 18 and the tire 32 to be disengaged from the remainder of the wheelassembly 10 in a simple and easy manner. For example, the lever arm 33may be coupled to a spring 35 that may bias the limiter 28 towards thecenterless rim 18. The limiter 28 may keep the centerless rim 18 inconsistent contact with the limiter 28 and/or the other roller guidesdue to the spring force of the spring 35. In some embodiments, as thelever arm 33 is rotated about a pivot point 37 (for example, by pullingor pushing the handle on the lever arm 33), the limiter 28 may be pulledaway from the centerless rim 18. After moving the limiter 28 away fromthe centerless rim 18, the centerless rim 18 and the tire 32 may bepulled away or drop away from the other components of the wheel assembly10 (e.g., from the exoskeleton plates and the roller guides).

In these and other embodiments, one or more roller guides may be used todrive the wheel assembly 10, for example, a roller guide at a sixo'clock position. There may be two idler roller guides, for example,between a nine o'clock position and the six o'clock position rollerguides. In these and other embodiments, the roller guides may be atdifferent locations between the nine o'clock/three o'clock positions andthe twelve o'clock position. However, in such an embodiment lever arm 33may not release the tire 32 and centerless rim 18 from the roller guidesand exoskeleton plates as the roller guides above the nine o'clock/threeo'clock position may maintain the connection between the roller guidesand the centerless rim 18.

In some embodiments, one or more of the bridging shafts may be securedto the first exoskeleton plate 13 and the second exoskeleton plate usingany suitable securing mechanisms, such as, for example, snap rings,threaded ends with nuts, quick-release levers with springs, etc. In someembodiments, the securing mechanisms may be disposed at outboard ends ofthe bridging shaft at least proximate the first and second exoskeletonplates. In some embodiments, removal of the securing mechanisms mayallow the rim 18 to drop from the exoskeleton assembly 12 for speedyremoval of the rim 18 and tire 32, which may facilitate replacementand/or repair of the rim 18 and/or the tire 32.

In some embodiments, the first exoskeleton plate 13 and/or the secondexoskeleton plate may be spaced apart from a first side and a secondside of the rim 18, respectively, such that there is a small gap betweenan interior surface of the first exoskeleton plate 13 and the first sideof the rim 18 and the second exoskeleton plate and the second side ofthe rim 18. For example, there may be a gap of approximately at leastone, two, three, four, five, ten, fifteen, etc. thousandths of an inch.In some embodiments, the first and second sides of the rim 18 may bevertical and/or may correspond to right and left sides of the rim 18,respectively.

In these and other embodiments, the rim 18 may be disposed proximate andbetween the first exoskeleton plate 13 and the second exoskeleton platewithout touching the first or second exoskeleton plates. For example,the first exoskeleton plate 13 may be disposed exterior to the firstside of the rim 18, and the second exoskeleton plate may be disposedexterior to the second side of the rim 18. In these and otherembodiments, in normal rotation, the rim 18 may not contact the first orthe second exoskeleton plates. Additionally or alternatively, inresponse to the rim 18 being subjected to a force that is counter to adirection of travel, the first and second exoskeleton plates mayphysically constrain the rim 18 such that the first side of the rim 18may contact the first exoskeleton plate 13 and/or the second side of therim 18 may contact the second exoskeleton plate. In these and otherembodiments, in response to the rim 18 being subjected to a force thatis counter to a direction of travel, a gap between the first exoskeletonplate 13 and the first side of the rim 18 and/or a gap between thesecond exoskeleton plate and the second side of the rim 18 may bereduced and/or eliminated. Thus, in some embodiments, the first and/orsecond exoskeleton plates may prevent the rim 18 from deviating from adesired direction of travel by more than the size of the gap (e.g., fivethousandths of an inch in either a left-hand or right-hand direction).

In some embodiments, the wheel assembly 10 may be configured to mitigaterotational friction by having only two points of contact with the rim18. The points of contact may occur at the first roller guide assembly14 and the second roller guide assembly 16. In these and otherembodiments, the first and/or second limiters 28, 30 may provideadditional points of contact in certain circumstances, such as inresponse to extreme forces, such as the drop, the compression, etc., andmay otherwise not be in physical contact with the rim 18 during normaloperation of the wheel assembly 10.

In some embodiments, the lips of the first and second exoskeleton platesmay include a low-friction coating disposed on an inner surface of aportion of the corresponding lip closest to the rim 18. The low-frictioncoating may reduce rotational friction and/or noise from any contactbetween the first and second exoskeleton plates and the rim 18 (e.g.,when the rim 18 departs from normal operation and scuffs against one ofthe exoskeleton plates).

Modifications, additions, or omissions may be made to FIG. 1 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 10 may include more or fewer elements than thoseillustrated and described in the present disclosure. For example, thewheel assembly 10 may include any number of roller guide assembliesdisposed at various locations around the exoskeleton assembly 12. Asanother example, the exoskeleton plates may take any shape or form thatprovides the functionality described in the present disclosure. Forexample, a square or rectangular plate without a void in the middle maybe utilized in the wheel assembly 10.

FIG. 2 illustrates an example embodiment of a wheel assembly 210 withone or more slots for one or more of the roller guide assemblies and/orlimiters. The wheel assembly 210 may be similar or analogous to thewheel assembly 10 of FIG. 1. In some embodiments, the relative positionof roller guide assemblies associated with the one or more slots may beadjusted by selectively moving the roller guide assemblies within theslots. In some embodiments, the wheel assembly 210 may include acenterless rim 218 (which may be similar or analogous to the rim 18 ofFIG. 1), a first roller guide assembly 214 (which may be similar oranalogous to the first roller guide 14 of FIG. 1), and a second rollerguide assembly 216 (which may be similar or analogous to the secondroller guide 16 of FIG. 1).

As illustrated, in some embodiments a first exoskeleton plate 213 (whichmay be similar or analogous to the exoskeleton plate 13 of FIG. 1) mayinclude one or more slots. For example, in the illustrated example, thefirst exoskeleton plate 213 may include a first slot 234 that maycorrespond to the first roller guide assembly 214 and may include asecond slot 236 that may correspond to the second roller guide assembly216). The second exoskeleton plate (not illustrated) may include one ormore slots aligned with the one or more slots of the first exoskeletonplate 213. In these and other embodiments, the corresponding slots ofthe first exoskeleton plate 213 may be sized and configured to beidentical or similar in size, shape, and/or orientation to correspondingslots in the second exoskeleton plate.

In some embodiments, the first roller guide assembly 214 may be disposedwithin the first slot 234 of the first exoskeleton plate and/or thesecond roller guide assembly 216 may be disposed within the second slot236 of the first exoskeleton plate 213. For example, a first end of thefirst bridging shaft of the first roller guide assembly 214 may bedisposed within the first slot 234 and/or a first end of the secondbridging shaft of the second roller guide assembly 216 may be disposedwithin the second slot 236. In some embodiments, a second end of thefirst bridging shaft may be disposed within a slot corresponding to thefirst slot 234 in the second exoskeleton plate. In these and otherembodiments, the second end of the second bridging shaft may be disposedwithin a slot corresponding to the second slot 236 in the secondexoskeleton plate.

In some embodiments, the first slot 234 and/or the second slot 236 maybe configured generally in an arc shape. The first roller guide assembly214 may be configured to selectively move within the first slot 234and/or the second roller guide assembly 16 may be configured toselectively move within the second slot 236. Adjusting a position of thefirst and/or the second roller guide assembly 214, 216 within the slots234, 236, and within corresponding slots in the second exoskeletonplate, may change an angle between the roller guide assemblies 214, 216with respect to a center of the wheel assembly 210. For example, bymoving the first roller guide assembly 214 within the first slot 234and/or a slot corresponding to the first slot 234 in the secondexoskeleton plate, and by moving the second roller guide assembly 216within the second slot 236 and a slot corresponding to the second slot36 in the second exoskeleton plate, the angle between the first rollerguide assembly 214 and the second roller guide assembly 216 may beadjusted to anywhere between approximately ten degrees (10°) and onehundred and forty degrees (140°) with respect to a center 211 of thewheel assembly 210. In some embodiments, the position of the firstroller guide assembly 214 in the first slot 234 and the position of thesecond roller guide assembly 216 in the second slot 236 may be adjustedsymmetrically. For example, if the first roller guide assembly 214 ismoved within the first slot 234 away from a six o'clock position (e.g.,analogizing the centerless wheel assembly 210 to a clock face), thesecond roller guide assembly 216 may be moved within the second slot 236approximately an equal distance away from the six o'clock position. Sucha symmetrical adjustment may balance the forces at the six o'clockposition. Additionally or alternatively, the adjustment may benon-symmetrical.

In some embodiments, the first and second roller assemblies 214, 216 maybe disposed in proximity or at a distance by virtue of the first andsecond roller assemblies 214, 216 being situated in the first and secondslots 234, 236, respectively, and in corresponding slots in the secondexoskeleton plate. In some embodiments, the first exoskeleton plate 213may include markings at least proximate the first slot 234 and/or thesecond slot 236 and/or the second exoskeleton plate may include markingsat least proximate a slot corresponding to the first slot 234 and/or aslot corresponding to the second slot 236, which may aid in positioningthe first and/or second roller assemblies 214, 216.

In some embodiments, the first and/or second roller assemblies 214, 216may be positioned within the first slot 234 and/or the second slot 236based on the intended use of the wheel assembly 210. For example, if thewheel assembly 210 is to be used in a low speed vehicle or a low speedsetting (e.g., less than ten miles per hour), the first and secondroller assemblies 214, 216 may be disposed closer together. As anotherexample, if the wheel assembly 210 is to be used in a high speed vehicleor a high speed setting (e.g., greater than ten miles per hour), thefirst and second roller guide assemblies 214, 216 may be disposedfurther apart.

In some embodiments, the rim 218 may be rotatably disposed about thefirst and second roller guides 214, 216, which may have shapescorresponding to a shape or profile of the rim 18. Longitudinal and/orangular adjustments of the first and second roller assemblies 214, 216within the first and second slot 234, 236, respectively, may be basedon, for example, rim diameters, dynamic run-out, or rim imperfections,which may decrease static friction between the first and second rollerguides of the first and second roller guide assemblies 214, 216 and therim 218. Longitudinal and/or angular adjustments of the first and/orsecond roller guide assemblies 214, 216 within the slots 234, 236, andslots corresponding to the slots 234, 236 in the second exoskeletonplate, may reduce scrubbing, which may occur, for example, when acornering load or braking forces are applied to the rim 218 by brakingdevices and/or an external payload. For example, adjusting the firstand/or the second roller guide assemblies 214, 216 within the slots 234,236 and slots corresponding to the slots 234, 236 in the secondexoskeleton plate may place the roller guide assemblies 214, 216 closerto the six o'clock position of the rim 218, creating a better rollingconnection and thus reducing shifting of the rim 218. Also, adjustmentof positions of the first and second roller assemblies 214, 216 withinthe first and second slot 234, 236, respectively, may allow the wheelassembly 210 to withstand shocks and/or impacts greater than aconventional spoked wheel may withstand because of the increased supportfrom the first exoskeleton plate 213 and the second exoskeleton plateand/or because the forces are distributed across a wider area than aconventional wheel.

In some embodiments, one end of a bridging shaft may be moved within aslot (e.g., the first slot 234) without adjusting the other end of thebridging shaft. Such a movement may create a different angle orelevation of the bridging shaft. By doing so, a scrubbing angle may bemodified when used in a side-by-side wheel vehicle or assembly. Forexample, in a side-by-side assembly with negative camber or when aside-by-side assembly is pivoted about the point where the wheelassembly 210 touches the ground, vectoring forces may dislodge one ormore of the roller guide assemblies (e.g., the first and/or secondroller guide assemblies 214, 216) from the rim 218. By adjusting theangle or elevation of the bridging shaft, the roller guide assembliesmay maintain contact with the rim even if subjected to such vectoringforces.

Modifications, additions, or omissions may be made to FIG. 2 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 210 may include more or fewer elements than thoseillustrated and described in the present disclosure. For example, thewheel assembly 210 may include any number of roller guide assembliesdisposed at various locations around the exoskeleton assembly. Asanother example, any number of the roller guide assemblies may have anassociated set of slots, including only one set of slots. As anadditional example, the slots may take any shape, size or configuration(e.g., a straight or angled line rather than an arc shape).

FIG. 3 illustrates an example embodiment of a wheel assembly 310 (whichmay be similar to the wheel assembly 10 and/or 210 of FIGS. 1 and/or 2)with a rim-braking mechanism 340. The rim-braking mechanism 340 mayinclude brake shoes 341, and may be disposed at least proximate thefirst and second exoskeleton plates. For example, the rim-brakingmechanism 340 may operate similar to a traditional bicycle rim brakewith a pad attached to the brake shoes 341 that may contact a centerlessrim 318 (which may be similar or analogous to the centerless rim 18 ofFIG. 1), slowing down the rim 318 and thus braking the tire 332.

In some embodiments, one or more stabilizer structures may be coupledwith portions of a first exoskeleton plate 313 (which may be similar oranalogous to the first exoskeleton plate 13 of FIG. 1) and a secondexoskeleton plate (not illustrated in FIG. 3). For example, a firststabilizer structure 342, including a first stabilizer wheel 344 thatrotates about a first stabilizer shaft 346, and a second stabilizerstructure (not illustrated in FIG. 3), including a second stabilizerwheel that rotates about a second stabilizer shaft, may be coupled withan outer portion of the first and second exoskeleton plate,respectively. In some embodiments, the stabilizer wheels (e.g., thefirst stabilizer wheel 344) may be horizontal and/or the stabilizershafts (e.g., the first stabilizer shaft 346) may be vertical. Whencornering forces are exerted on an exoskeleton assembly 312 (which maybe similar or analogous to the exoskeleton assembly 12 of FIG. 1) and/orthe rim 318, the first stabilizer wheel 344 and/or the second stabilizerwheel may contact the rim 318 and oscillation, vibration, and/ordisplacement of the rim 318 may decrease.

In some embodiments, the first stabilizer wheel 344 and/or the secondstabilizer wheel may be spaced apart from the first and second side ofthe centerless rim 318, respectively, by a gap. For example, there maybe a gap of approximately at least one, two, three, four, five, ten,fifteen, etc. thousandths of an inch. When the cornering forces areexerted on the exoskeleton assembly 312 and/or the rim 18, such as whenstriking a pothole or when stopping abruptly, for example, the gapbetween the first stabilizer wheel 344 and the first side of the rim 318and/or the gap between the second stabilizer wheel and the second sideof the rim 318 may be reduced or eliminated. When in physical contactwith the rim 318, the first stabilizer wheel 344 and/or the secondstabilizer wheel may be shaped, disposed, and/or configured to rollalong the rim 318 without slipping based on static friction. In someembodiments, there may be slipping between the first and/or secondstabilizer wheels and the rim 318.

Modifications, additions, or omissions may be made to FIG. 3 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 310 may include more or fewer elements than thoseillustrated and described in the present disclosure. For example, thewheel assembly 310 may include any number of roller guide assembliesdisposed at various locations around the exoskeleton assembly. Asanother example, any number of the roller guide assemblies may have anassociated set of slots, including only one set of slots. As anadditional example, the slots may take any shape, size or configuration(e.g., a straight or angled line rather than an arc shape).

FIG. 4 illustrates a cutaway view of a wheel assembly 410 (which may besimilar to the wheel assembly 10, 210, and/or 310 of FIGS. 1, 2, and/or3). In some embodiments, the wheel assembly 410 may include a centerlessrim 418 and a tire 432 (which may be similar or analogous to thecenterless rim 18 and the tire 32 of FIG. 1), a first roller guideassembly 414 with a first roller guide 424 and a first bridging shaft415 (which may be similar or analogous to the first roller guideassembly 14, first roller guide 24, and first bridging shaft 15 of FIG.1), an exoskeleton assembly 412 with a first exoskeleton plate 413(which may be similar or analogous to the exoskeleton assembly 12 andthe first exoskeleton plate 13 of FIG. 1. In some embodiments, the firstroller guide assembly 414 may include one or more first primary bearings448, which may be configured to rotate about the first bridging shaft415. In some embodiments, the first bridging shaft 415 may be coupledwith the first exoskeleton plate 413 and the second exoskeleton plate454.

As illustrated in FIG. 4, in some embodiments, the first roller guideassembly 414 may also include a first roller guide 424 configured toinclude a shape or profile that matches a corresponding shape or profileof the rim 418. In some embodiments, the first roller guide 424 mayinclude a concave shape that corresponds to a convex shape of the rim418.

In some embodiments, the first exoskeleton plate 413 may include adistal portion 456 about an outer circumference or outer edge of thefirst exoskeleton plate 413. Similarly, in some embodiments, the secondexoskeleton plate 454 may include a distal portion 458 about an outercircumference or outer edge of the second exoskeleton plate 454. In someembodiments, the distal portions 456, 458 may be disposed further fromthe center of the wheel assembly 410 than one or more of the following:the first bridging shaft 450, the second bridging shaft (not illustratedin FIG. 4), the third bridging shaft 460, and the fourth bridging shaft462. In some embodiments, the wheel assembly 410 may include a firstlimiter including a third bridging shaft 460 and a second limiterincluding a fourth bridging shaft 462. In some embodiments, the firstlimiter may include a roller guide assembly with one or more bearings(not illustrated in FIG. 4), a roller guide (not illustrated in FIG. 4),etc. In these and other embodiments, the second limiter may beimplemented in a similar or identical manner to the first limiter, orimplemented in a different manner.

In some embodiments, the rim 418 may be spaced apart from one or more ofthe following by a gap: the distal portions 456, 458 of the first andsecond exoskeleton plates 452, 454, the first limiter, the thirdbridging shaft 460, the fourth bridging shaft 462, and/or an expansionbushing 464 (which may be similar or analogous to the expansion bushing64 of FIG. 1). For example, there may be a gap of approximately at leastone, two, three, four, five, ten, fifteen, etc. thousandths of an inch.For example, a first side 466 of the rim 18 may be spaced apart from thedistal portion 456 of the first exoskeleton plate 413 by a first gap 472and/or a second side 468 of the centerless rim 418 may be spaced apartfrom the distal portion 459 of the second exoskeleton plate 454 by asecond gap 474. In these and other embodiments, the first gap 472 andthe second gap 474 may be the same, or may be different. As anotherexample, the third and fourth bridging shafts 460, 462 or roller guidescoupled with the third and fourth bridging shafts 460, 462 may each bespaced apart from an interior circumference or centerline 480 of the rim418 by a third gap 476 and a fourth gap 478, respectively. In these andother embodiments, the third gap 476 and the fourth gap 478 may be thesame, or may be different. One or more of the third and fourth gaps 476,478 may be reduced or eliminated in response to the exoskeleton assembly412 experiencing a drop from an elevation and/or a compression due to agreat force or impact such as, for example, an abrupt or sudden stop.The third and fourth bridging shafts 460, 462 or roller guides coupledwith the third and fourth bridging shafts 460, 462 may contact thecenterline 480 of the centerless rim 418 in response to the drop and/orthe compression, which may mitigate effects of the drop and/or thecompression.

As illustrated in FIG. 4, in some embodiments, the exoskeleton assembly412 may include a connecting hoop 482, which may join the first andsecond exoskeleton plates 413, 454 and/or the first and secondstabilizer structures 442, 489 (which may be similar or analogous to thefirs stabilizer structure 42 of FIG. 3). In some embodiments, theconnecting hoop 482 may bridge the tire 432. In some embodiments, theconnecting hoop 482 may be disposed at an upper portion or top of thecenterless wheel assembly 410. For example, the centerless wheelassembly 410 may contact the ground at one-hundred and eighty degrees(e.g., a six o'clock position), while the connecting hoop 482 may bedisposed at zero degrees (e.g., a twelve o'clock position). Theconnecting hoop 482 may provide added structural support for a firststabilizer wheel 444 (which may be similar or analogous to the firsstabilizer wheel 44 of FIG. 3) and the second stabilizer wheel 484. Insome embodiments, the centerless rim 418 may be sized and/or configuredto fit between the first and second exoskeleton plates 413, 454, thefirst and second exoskeleton pates 413, 454 constraining the centerlessrim 418 and/or acting as a track or guide for the centerless rim 418.

In some embodiments, the first stabilizer wheel 444 and the secondstabilizer wheel 484 may rotate with respect to the first stabilizershaft 446 and the second stabilizer shaft 486 (which may be similar oranalogous to the firs stabilizer shaft 46 of FIG. 3), respectively. Insome embodiments, the first and second stabilizer shafts 446, 486 andthe first and second stabilizer wheels 444, 484 may be supported byfirst and second stabilizer structures 442, 489. In response tooscillation of the rim 418, and the rim 418 contacting the firststabilizer wheel 444 and/or the second stabilizer wheel 484, the firststabilizer wheel 444 and/or the second stabilizer wheel 484 may rotateto minimize rotational friction and/or may prevent or inhibit the rim418 from oscillating by more than a width of a gap between thestabilizer wheels 444, 484 and the rim 418. For example, the rim 418 mayoscillate by no more than five-thousandths of an inch to either side dueto contact with the stabilizer wheels 444, 484 in some embodiments.Oscillation of the centerless rim 418 may occur, for example, when thetire 432 strikes or impacts a fixed object and/or an obstruction.Horizontal deflection of the centerless rim 418 by the stabilizer wheels444, 484 in response to oscillation of the centerless rim 418 mayfacilitate predictable tracking of the tire 432 and may reducerotational friction.

In some embodiments, the first roller guide 424 may be configured toinclude a shape or profile that matches a corresponding shape or profileof the centerless rim 418, which may reduce rotational friction and/orscrubbing. In some embodiments, the shape or profile of the roller guide424 may be based on an intended use of the wheel assembly 410. Forexample, if used in a side-by-side wheel configuration, forces aredifferent than for an in-line wheel configuration. In a side-by-sideconfiguration, the roller guide 424 may have a spherical shape. By usinga spherical shape, as cambering, wheel speed, adjusting bridging shaftsin slots, etc. change the orientation of the roller guide 424 with therim 418, the roller guide 424 may maintain contact with the rim 418.Such a shape may allow for other mitigation of scrubbing or othervectoring forces while maintaining contact between the roller guide 424and the rim 418. As another example, by having the first roller guide424 match a profile of the centerless rim 418, the surface area incontact between the first roller guide 424 and the centerless rim 418may be maximized, decreasing the likelihood of slipping by matchingtorque requirements.

In some embodiments, the centerless rim 418 may slope downward to eitherside of the centerline 480. In some embodiments, a first sloped portion488 may be disposed at least proximate the first side 466 of thecenterless rim 418 and/or a second sloped portion 490 may be disposed atleast proximate the second side 468 of the centerless rim 418.

In some embodiments, the centerless rim 418 may be oriented verticallywith respect to the ground. In some embodiments, the centerless rim 418may include one or more longitudinal or angular grooves 492 disposedalong the sloped portions 488, 490 and/or the sides 466, 468 of thecenterless rim 418. For example, the grooves 492 may be in relief on thesurface of the centerless rim 418. The grooves 492 may facilitateremoval of water, grime, debris, and/or foreign material from thecenterless rim 418, which may increase static friction between surfacesof the first and second roller guides and the centerless rim 418. Forexample, due to gravitational and/or centrifugal forces, water, grime,debris, and/or other foreign material may gravitate to the grooves 492and along the grooves 492 towards an edge of the centerless rim 418 andoff of the centerless rim 418.

In some embodiments, the exoskeleton assembly 412 may additionallyinclude cladding that may provide a covering over any moving parts toincrease aerodynamics, for example by reducing turbulence, drag, airresistance, wind resistance, etc. For example, a smooth form factorcladding may overlay the first and second exoskeleton plates 413, 454 toenclose any moving parts (e.g., the roller guide assembly 414). In someembodiments, the cladding may also include a void in material about themiddle of the centerless wheel assembly 410. In some embodiments, thegrooves 492 may be included the cladding. In these and otherembodiments, the cladding and the first and second exoskeleton plates413, 454 may be combined into a single piece of material to furtherreduce weight and improve aerodynamics, turbulence, drag, airresistance, wind resistance, etc. For example, in some embodiments(e.g., as illustrated in FIG. 6C), the first and second exoskeletonplates 413, 454 and/or the cladding may form a generally U-shapedprofile. As another example, the first and second exoskeleton plates413, 454 and/or the cladding may form an asymmetrical shape (e.g., withthe leading and trailing edges aerodynamically optimized). In these andother embodiments, the increased performance in aerodynamics may offsetperformance tradeoffs due to a friction-based drive system, For example,at speeds above twenty miles per hour, the increased aerodynamicperformance due to the lack of spokes and the U-shaped profile mayovercome any observed performance loss due to friction.

Modifications, additions, or omissions may be made to FIG. 4 withoutdeparting from the scope of the present disclosure. For example, thecenterless wheel assembly 410 may include more or fewer elements thanthose illustrated and described in the present disclosure.

FIG. 5 illustrates a diagram representing an example wheel assembly 510(which may be similar to the wheel assembly 10, 210, 310, and/or 410 ofFIGS. 1, 2, 3, and/or 4). For example, as illustrated in FIG. 5, one ormore of the roller guide assemblies may be a drive friction roller guideassembly, such as a first friction roller guide assembly 597. Such afriction roller guide assembly may be shaped, sized, and/or configuredto be in constant or near constant physical contact with a centerlessrim 518 (which may be similar or analogous to the centerless rim 18 ofFIG. 1) such that the friction roller guide assembly may roll along therim 518. For example, if the first friction roller guide assembly 597 iscaused to rotate (e.g., by a motor or other motive force), staticfriction between the first friction roller guide assembly 597 and therim 518 may cause the rim 518 to rotate.

In some embodiments, the first friction roller guide assembly 597 mayinclude a driven shaft with keys that allow the rim 518 to be driven bythe first friction roller guide assembly 597. For example, a firstbridging driven shaft 595 of the first friction roller guide assembly597 may have keys, teeth, or other features to engage or otherwise locka roller guide of the first friction roller guide assembly 597 to thefirst bridging driven shaft 595. Using the keys, teeth, or otherfeatures, when the first bridging driven shaft 595 is rotated, thecorresponding roller guide may also rotate.

In some embodiments a torque may be applied to the first bridging drivenshaft 595, for example, by a motor, crank, or other motive force. Inresponse to the torque being applied to the first bridging driven shaft595, the first friction roller guide assembly 597 may rotate the rim 518by virtue of static friction between the first friction roller guideassembly 597 and the rim 518. Thus, the rim 518 may function as both anoutput gear and a driven wheel. In some embodiments, the first frictionroller guide assembly 597 may have a small diameter compared to adiameter of the rim 518, allowing a high gear ratio. The high gear ratiomay offer a mechanical advantage over conventional wheels and/orconventional power transmission models and may improve efficiency,reduce weight, and/or reduce cost. In some embodiments, such a high gearratio may include a ratio of between approximately seven to one andapproximately one hundred and twenty-five to one. In these and otherembodiments, the gear ratio may be based on the intended use of thewheel assembly. Additionally or alternatively, the gear ratio may bebased on a size of the wheel, which may be limited in size based on theapplication. For example, a vehicle may be limited in wheel size to theexpected height of the vehicle, etc. In some embodiments a planetarygear may be used, for example, by being coupled to the first bridgingdriven shaft 595.

In some embodiments, the wheel assembly 510 may be configured to have anopen center or a void of material in the center of the wheel assembly510, which may provide a storage region with spatial capacity forstorage of any of a variety of items such as a mechanized drive, cargo,fuel tanks, motors, engines, battery packs, luggage, an electricitystorage system, etc.

In some embodiments, a second bridging shaft 593 of a second rollerassembly (which may be similar to the second roller guide assembly 16 ofFIG. 1) may be non-symmetrically disposed relative to the first bridgingdriven shaft 595 about a center 511 of the wheel assembly 510. Forexample, the second bridging shaft 593 may be disposed slightly higherthan the first bridging driven shaft 595. For example, the secondbridging shaft 593 may be disposed one, two, three, four, five, ten,fifteen, twenty, etc. thousandths of an inch above the first bridgingdriven shaft 595. In some embodiments, compression of the first frictionroller guide assembly 597 may occur when the exoskeleton assembly 512 ispushed downward against the rim 518 in response to a payload beingexerted on the exoskeleton assembly 512 (e.g., a person getting on abicycle with centerless wheels), and the rim 518 is pushed upward by acountering force of the ground. The compression may cause the heightbetween the first bridging driven shaft 595 and a center of the secondbridging shaft 593 to close to zero and may cause that a high staticfriction be produced between the first friction roller guide assembly 97and the rim 518.

In some embodiments, an angle between the first friction roller guideassembly 597 and the second roller guide assembly 516 may be differentthan when not using a drive roller guide assembly. For example, in someembodiments, the angle between the first friction roller guide assembly597 and the second roller guide assembly 516 may be betweenapproximately sixty degrees and one hundred and forty degrees. The anglemay also include an angle between ten degrees and one hundred and fortydegrees.

Modifications, additions, or omissions may be made to FIG. 5 withoutdeparting from the scope of the present disclosure. For example, thecenterless wheel assembly 510 may include more or fewer elements thanthose illustrated and described in the present disclosure. For example,the centerless wheel assembly 510 may include any number of drive and/orfriction roller guide assemblies disposed at various locations aroundthe exoskeleton assembly 512. As another example, the centerless wheelassembly 510 may include any motor, engine, crank, etc. which mayprovide torque to the first bridging driven shaft 595.

FIGS. 6A and 6B illustrate cross-sectional views of a portion of examplewheel assemblies 610 a and 610 b, respectively (which may be similar tothe wheel assemblies 10, 210, 310, 410, and/or 510 of FIGS. 1, 2, 3, 4,and/or 5). The wheel assemblies 610 a and 610 b may illustrate exampleprofiles and/or form factors for centerless rims (e.g., a concavecenterless rim 618 a in FIG. 6A and a convex centerless rim 618 b inFIG. 6B) and roller guides (e.g., a convex roller guide 699 a in FIG. 6Aand a concave roller guide 699 b in FIG. 6B). In some embodiments, thewheel assemblies 610 a and 610 b may include drive friction roller guideassemblies.

In some embodiments, the first roller guides 699 a and 699 b may includea shape or profile that matches a corresponding shape or profile of therims 618 a and 618 b, respectively. For example, the first roller guide699 a may include a convex shape and the rim 618 a may include a concaveshape, as illustrated in FIG. 6A. As another example, the first rollerguide 699 b may include a concave shape and the rim 618 b may include aconvex shape, as illustrated in FIG. 6B. While the remaining descriptionmay be described with reference to FIG. 6A, the disclosure is equallyapplicable to FIG. 6B.

Static friction between the first roller guide 699 a and the rim 618 amay drive the rim 618 a with minimal frictional losses and minimalscrubbing on an outer surface of first roller guide 699 a. For example,because the shape and/or profile of the first roller guide 699 a and therim 618 a are generally matched, the surface area between the firstroller guide 699 a and the rim 618 a may be maximized, thus reducingslippage between the first roller guide 699 a and the rim 618 a.

In some embodiments, a first friction roller guide assembly 697 a mayinclude first one-way bearings 691. In some embodiments, a firstbridging driven shaft 695 a may include a driven shaft with a key 698.The key 698 may lock the first roller guide 699 a with the firstbridging driven shaft 695 a such that the first bridging driven shaft695 a and the first roller guide 699 a move as a single body (e.g., whenthe first bridging driven shaft 695 a rotates, the first roller guide699 a also rotates). Using the key 698, when the first bridging drivenshaft 695 a is rotated, static friction between the interior of the rim618 a and the first roller guide 699 a may rotate the rim 618 a. In someembodiments, the first roller guide 699 a may function as an input gearand the interior of the rim 618 a may function as an output gear, thus,constituting a first stage of gear reduction. For example, the gearreduction may include a ratio of between approximately forty to one andtwo to one. For example, an electric scooter or car may have a gearreduction of thirty-five to one. As another example, a wheelchair mayutilize a gear ratio (rather than reduction) of one hundred andtwenty-five to one.

FIG. 6C illustrates a cross sectional view of a portion of anotherexample profile of a wheel assembly 610 c (which may be similar to thewheel assemblies 10, 210, 310, 410, and/or 510 of FIGS. 1, 2, 3, 4,and/or 5). In some embodiments, the wheel assembly 610 c may include adrive roller guide assembly or an idler roller guide assembly. The wheelassembly 610 c may additionally include bearings 691 c (which may besimilar or analogous to the bearings 691 a and 691 b of FIGS. 6A and 6B)and bridging shaft 695 c (which may be similar or analogous to theshafts 695 a and 695 b of FIGS. 6A and 6B).

As illustrated in FIG. 6C, the rim 618 c may include a generally flatprofile abutting the surface of the roller guide 699 c. The rim 618 cmay additionally include a rail 650 with a corresponding void 660 in theroller guide 699 c. In these and other embodiments, the rim 618 c andthe roller guide 699 c may be positioned and sized such that gaps 672and 674 may exist between the roller guide 699 c and the rail 650.Additionally or alternatively, there may be such a gap completelybetween the roller guide 699 c and the rail 650 such that in normaloperation, the roller guide 699 c may not contact the rail 650. In someembodiments, the rail 650 may serve as a guide or a stop to prevent theroller guide 699 c from losing contact with the rim 618 c. For example,when hitting a pothole, or when turning, forces may be applied to thewheel assembly 610 c that may cause one or more of the roller guides(e.g., the roller guide 699 c) to disengage from the rim, and may evencause the entire assembly of roller guides and/or exoskeleton plates todisengage from the rim and the tire. Such a concern and problem may beparticularly observed in an embodiment in which two wheels are side byside, such as a wheelchair or an automobile. In such embodiments, theinside wheel, when turning, may experience strong side-ways forces thatmay push the roller guides and/or the exoskeleton plates out ofconnection with the rim. In these and other embodiments, the rail 650may act as a guide or a stop to keep the roller guide (e.g., the rollerguide 699 c) in contact with the rim 618 c, and/or to keep the rollerguides from derailing.

In some embodiments, the profile of the exoskeleton plate 612 mayinclude a generally U-shaped profile. For example, rather than havingtwo distinct exoskeleton plates, the exoskeleton plate 612 may include afirst portion that supports one end of the bridging shafts and a secondportion that supports the other end of the bridging shafts. Theexoskeleton plate 612 may also include a curved connecting portion thatconnects the first and the second portions. The generally U-shapedprofile may provide increased aerodynamic performance and may reducedrag. Additionally or alternatively, a single-piece exoskeleton plate612 (whether the U-shaped profile illustrated or otherwise) may providetorsional rigidity and/or weight reduction. For example, the exoskeletonplate 612 may more effectively resist forces that may warp theexoskeleton plates and may require less material overall (and thus lessweight) than a two-exoskeleton plate design.

Modifications, additions, or omissions may be made to FIG. 6A, 6B, or 6Cwithout departing from the scope of the present disclosure. For example,the wheel assemblies 610 a, 610 b, and/or 610 c may include more orfewer elements than those illustrated and described in the presentdisclosure. For example, the first roller guide 699 a and/or the rim 618a may take any shape, form or profile.

FIG. 7 illustrates a diagram of an example wheel assembly 710 (which maybe similar to the wheel assemblies 10, 210, 310, 410, 510, 610A, and/or610B of FIGS. 1, 2, 3, 4, 5, 6 a, and/or 6 b) that may be driven. Insome embodiments, a first bridging driven shaft 795 (which may besimilar or analogous to the first bridging driven shaft 595 of FIG. 5)of a first friction roller guide assembly 797 (which may be similar oranalogous to the first friction roller guide assembly 597 of FIG. 5) mayinclude a driven shaft with a key 798. The key 798 may operate asdescribed with respect to the key 698 of FIG. 6a such that the firstbridging driven shaft 795 and the first friction roller guide assembly797 move as a single body. In some embodiments, the first bridgingdriven shaft 795 may be operably coupled to a first sprocket, firstpulley, or first right angle gear, which may be operably coupled to afirst chain, first drive shaft, or first belt 705. In some embodiments,the first belt 705 may be operably coupled to a second sprocket, secondpulley, or second right-angle gear 702, which may be operably coupled toan output shaft of an engine or electric motor 704. Coupling between thefirst right-angle gear and the second right-angle gear may constitute asecond state of gear reduction. In some embodiments, the second state ofgear reduction may include a ratio of between approximately two to oneand approximately ten to one, for example, five to one. In these andother embodiments, the internal diameter of the rim may dictate of thevalue of the second gear reduction. Thus, in aggregate, going from themotor 704 to the rotation of the wheel, there may be an overall ratio ofbetween approximately two to one and approximately one hundredtwenty-five to one.

When an external source of energy or power from the electric motor 704is applied to the second right-angle gear 702, the second right-anglegear 702 may rotate, in turn causing the first belt 705 to rotate. Thefirst belt 705 rotating may cause the first sprocket, first pulley, orfirst right angle gear associated with the first bridging driven shaft795 to rotate. Rotation of the first bridging driven shaft 795 mayrotate one-way bearings 791 (which may be similar or analogous toone-way bearings 699 a of FIG. 6A) and a first friction roller guide 799(which may be similar or analogous to the first friction roller guide699 a of FIG. 6A). Because of static friction between the first frictionroller guide 799 and the rim 718, rotation of the first friction rollerguide 799 rotating may cause the rim 718 to rotate.

In some embodiments, the engine or electric motor 704 may include anysource of motive power. For example, the engine or electric motor 704may include an electric motor such as a direct current (DC) motor, analternating current (AC) motor, a brush motor, a brushless motor, ashunt wound motor, a separately excited motor, a series wound motor, acompound wound motor, a permanent magnet motor, a servomotor, aninduction motor, a synchronous motor, a linear induction motor, asynchronous linear motor, etc. As another example, the engine orelectric motor 704 may include a fuel consuming engine, such as a fourstroke engine, a diesel engine, a two stroke engine, a Wankel engine, anAtkinson engine, a gnome rotary engine, etc. In some embodiments, theengine or electric motor 704 may include a small, high-speed,high-efficiency DC electric motor that may rotate at speeds greater thansix thousand rotations per minute (RPM). In these and other embodiments,the use of such a small motor may be available because of the gearingratio from the drive roller guide 799 to the rim 718. As an additionalexample, the engine or electric motor 704 may include a human-poweredmotive device, such as bicycle pedals, arm cranks, ratcheting levers,etc.

In some embodiments, slippage may occur between the first frictionroller guide 799 and the rim 718. For example, during rainy conditionsor when dust, debris, or any other material gets between the firstfriction roller guide 799 and the rim 718, the rotational force of thefirst friction roller guide 799 may overcome the static friction betweenthe first friction roller guide 799 and the rim 718. In someembodiments, the present disclosure may include components and/orfeatures to detect such slippage and/or to provide a corrective action.Additionally or alternatively, some embodiments of the presentdisclosure may include components and/or features to detect the end ofsuch slippage and/or to stop providing a corrective action.

In some embodiments, multiple sensors 735 may be distributed throughoutthe wheel assembly 710 to facilitate slippage control. The sensors 735may be configured to measure the speed of various components in thewheel assembly 710. For example, a first sensor 735 a may be disposed inassociation with the motor 704 to measure a rotational speed of theright angle gear 702. A second sensor 735 b may be disposed inassociation with an idler roller guide 716 that may not be driven tomeasure a rotational speed of the idler roller guide 716. A third sensor735 c may be disposed in association with the rim 718 and/or a wheel732. The sensors 735 may include any device, component, or combinationthereof configured to sense position, velocity, acceleration, or anycombinations thereof. For example, the sensors 735 may include acapacitive sensor, a potentiometer, a proximity sensor, an inductivesensor, an accelerometer, a gyroscope, a magnetometer, etc., or anycombinations thereof. In some embodiments, the sensors 735 may worktogether to determine any of position, velocity, and/or acceleration.

In some embodiments, the sensors 735 may be communicatively coupled to acomputing device 745. The computing device 745 may be configured tomonitor the speeds of various components of the wheel assembly 710 andadjust the power delivered to the motor 704 accordingly or otherwisealter the operation of the wheel assembly 710. Such monitoring andadjustment may be described with greater detail in FIGS. 25A-B and 26.The computing device 745 may include any special purpose or generalcomputing device. For example, the computing device 745 may include amicroprocessor, a microcontroller, a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a Field-ProgrammableGate Array (FPGA), or any other digital or analog circuitry configuredto interpret and/or to execute program instructions and/or to processdata. The computing device 745 may also include some computer-readablemedium, such as a data storage device or memory.

In some embodiments, the computing device 745 may monitor or measure thespeeds of various components of the wheel assembly 710 relative to eachother. For example, the computing device 745 may monitor the speed ofthe first friction roller guide 799 relative to the idler roller guide716. As another example, the computing device 745 may monitor the speedof the rim 718 relative to the right angle gear 702. As an additionalexample, the computing device 745 may monitor the speed of the rim 718relative to the right angle gear 702. In these and other embodiments,under normal operation without slippage, a proportional relationship mayexist between the various components monitored. For example, dependingon the placement of the sensors 735 and the diameters of the variouscomponents of the wheel assembly 710, a certain rotational speed of theright angle gear 702 may correspond to a certain speed of the firstfriction roller guide 799, the idler roller guide 716, and/or the rim718 or the wheel 732. If slippage occurs, the speed of the right anglegear 702 and/or the first friction roller guide 799 may increase beyondor outside of the normal operational relationships.

In some embodiments, when the speed of the right angle gear 702 and/orthe first friction roller guide 799 extends outside of the normaloperational relationship, the computing device 745 may invoke acorrective action to counteract the slippage. For example, the computingdevice 745 may take an action to adjust the power or rate of speed ofthe motor 704 or may take an action to adjust the first friction rollerguide 799. Such corrective actions may be discussed in greater detailwith respect to FIGS. 25A-B and 26.

Modifications, additions, or omissions may be made to FIG. 7 withoutdeparting from the scope of the present disclosure. For example, thecenterless wheel assembly 710 may include more or fewer elements thanthose illustrated and described in the present disclosure. For example,the centerless wheel assembly 710 may include any number of gears and/orconnections between the first bridging driven shaft 795 and the engineor electric motor. As another example, any type of chain, belt, driveshaft, or other connector may be used to connect the various gearsand/or connections.

FIG. 8A illustrates a top cutaway view of an example wheel assembly 810(which may be similar to the wheel assemblies 10, 210, 310, 410, 510,610 a, 610 b, and/or 710 of FIGS. 1, 2, 3, 4, 5, 6A, 6B, and/or 710) andFIG. 8B illustrates a diagram of the wheel assembly 810 of FIG. 8A.

In some embodiments, an output shaft 802 of an engine or electric motor804 may be operably coupled with a first sprocket, first pulley, orfirst right-angle gear 812. In some embodiments, the first right-anglegear 812 may be coupled with a chain, drive shaft, or belt 814, whichmay be operably coupled with a second sprocket, second pulley, or secondright-angle gear 816. In some embodiments, the second right-angle gear816 may be operably coupled with any bridging shaft, such as, forexample, a bridging driven shaft 895 (which may be similar to thebridging driven shaft 695 of the first friction roller guide assembly697 a of FIG. 6A).

In some embodiments, the bridging driven shaft 895 may be coupled withan input gear 828. When power or energy is supplied to the electricmotor 804, by, for example, an electricity storage system, storagebattery, or fuel source 820, torque may be applied to the firstright-angle gear 812, which may rotate the belt 714. Rotation of thebelt 814 may in turn rotate the second right angle-gear 816, which mayrotate the bridging driven shaft 895, which may rotate the input gear818. In some embodiments, the centerline 880 of the rim 818 may includean output gear 822, which may be driven by the input gear 828. Whileillustrated as a gear in FIGS. 8a and 8b , the same gearing relationshipmay be experienced by friction based rotation. For example, in someembodiments, the input gear 828 may include a roller guide (e.g., thefirst friction roller guide 699 a of FIG. 6A) and the centerless rim 818may directly interface with the roller guide. In some embodiments, apinion and ring gear may be used, for example, in high horsepowerconditions such as above fifty horsepower from an electric motor.

In some embodiments, a hybrid system may be utilized. For example, insome embodiments, two different wheel diameters may be used and bothwheels may be driven (e.g., a front wheel and a back wheel). Forexample, the smaller of the wheels may be used as a low gear range forhill climbing performance and the larger wheel may be used for topspeed. By using the two wheel sizes, a two-speed transmission mayeffectively be introduced.

A gear ratio between the output gear 822 and the input gear 828 may belarger than is possible within a single stage of reduction in the caseof a conventional wheel. For example, the ratio may include betweenapproximately five to one and approximately one hundred and twenty-fiveto one. This gearing advantage of the centerless wheel assembly 810 mayfacilitate additional economies of weight and space saving via adaptionto a more dimensionally compact motor 804 (e.g., a brushless electricmotor), which may otherwise, due to its small size and/or high RPM,provide insufficient torque for a conventional wheel. The gearingadvantage of the centerless wheel assembly 810 may also decrease one ormore of the following: the amount of current or power necessary for avehicle coupled with the centerless wheel assembly 810 to overcomeinertia, resistive losses, and the operating temperature of the electricmotor 804, such that efficiency of the vehicle may be improved.

Modifications, additions, or omissions may be made to FIGS. 8a and 8bwithout departing from the scope of the present disclosure. For example,the centerless wheel assembly 810 may include more or fewer elementsthan those illustrated and described in the present disclosure. Forexample, the centerless wheel assembly 810 may include the input gear828 that may interface with the output gear 822 and may also include oneor more friction-based rollers. As another example, the centerless rim818 may include a profile with multiple protrusions, one that matches afriction based roller guide and one with teeth to function as the outputgear 822.

FIG. 9 illustrates a diagram of an example wheel assembly 910 (which maybe similar to the wheel assemblies 10, 210, 310, 410, 510, 610 a, 610 b,710, and/or 810 of FIGS. 1, 2, 3, 4, 5, 6A, 6B, 7, 8A, and/or 8B) thatmay include an exterior input driver 924 that may drive a tire 932(which may be similar or analogous to the tire 32 of FIG. 1). In someembodiments, the exterior input driver 924 may drive the tire 932 withan external friction roller 928. For example, the external frictionroller 928 may be similar to a roller guide assembly that operates onthe internal side of a centerless rim (e.g., the first friction rollerguide 697 a and the centerless rim 618 a of FIG. 6A). The externalfriction roller 928 may be shaped, sized, and or otherwise configured tointerface with the external side of the tire 932. For example, theexternal friction roller 928 may have a concave shape that matches aconvex profile of the external side of the tire 932. Static frictionbetween the external friction roller 928 and the tire 932 may cause theexternal friction roller 928 to roll along the tire 932 such that as theexternal friction roller 928 is caused to rotate, the tire 932 is alsocaused to rotate. In these and other embodiments, the exterior inputdriver 924 may be caused to rotate (e.g., from a motor or engine such asthe motor 804 of FIG. 8A), which may rotate a drive shaft, chain, orbelt 926 to rotate. Rotation of the drive shaft, chain, or belt 926 maycause the external friction roller 928 to rotate. Rotation of theexternal friction roller 928 may cause the tire 932 to rotate, thusdriving the tire 932.

In some embodiments, a hybrid centerless wheel assembly may be used. Forexample, such a centerless wheel assembly may include one or morefriction roller assemblies that may provide rolling force against theinternal edge of a centerless rim, and may also include one or moreexternal friction rollers that may provide rolling force against theexternal edge of a tire.

Modifications, additions, or omissions may be made to FIG. 9 withoutdeparting from the scope of the present disclosure. For example, thecenterless wheel assembly 910 may include more or fewer elements thanthose illustrated and described in the present disclosure. For example,the centerless wheel assembly 910 may include a friction rollerassembly.

FIGS. 10A and 10B illustrate a top cutaway view and a diagram,respectively, of a dual-driving example wheel assembly 1010 (which maybe similar to the wheel assemblies 10, 210, 310, 410, 510, 610 a, 610 b,710, 810, and/or 910 of FIGS. 1, 2, 3, 4, 5, 6A, 6B, 7, 8A, 8B, and/or9). In some embodiments, the wheel assembly 1010 may includedual-driving friction roller guide assemblies. For example, the wheelassembly 1010 may include a first friction roller guide assembly 1097(which may be similar or analogous to the first friction roller guide697 a of FIG. 6A), which may include one or more of the following: afirst bridging driven shaft 1095 (which may be similar or analogous tothe first bridging driven shaft 695 a of FIG. 6A) with a key, one ormore first one-way bearings 1091 (which may be similar or analogous tothe one way bearings 691 of FIG. 6A), and a first friction roller guide1099 (which may be similar or analogous to the first friction rollerguide 699 a of FIG. 6A). In some embodiments, the wheel assembly 1010may also include a second friction roller guide assembly 1036, which mayinclude one or more of the following: a second bridging driven shaft1038 with a key, one or more second one-way bearings 1040, and a secondfriction roller guide 1042. In some embodiments, the second centerlessfriction roller guide assembly 1036 may be similar or equivalent to thefirst centerless friction roller guide assembly 1097.

In some embodiments, the first bridging driven shaft 1095 may be coupledwith a first sprocket, a first pulley, or a first right angle gear 1044,and a first end of the second bridging driven shaft 1038 may be coupledwith a second sprocket, a second pulley, or a second right angle gear1046. In some embodiments, the first right angle gear 1044 and thesecond right angle gear 1046 may be operably coupled to a first chain,first drive shaft, or first belt 1047. In some embodiments, a second endof the second bridging driven shaft 1038 may be coupled to a thirdsprocket, a third pulley, or a third right angle gear 1048. In someembodiments, a second chain, second drive shaft, or second belt 1050 maybe coupled to the third right angle gear 1048 and an output shaft of anengine or electric motor 1004.

The electric motor 1004 may be used as an external source of energy orpower, which may be used to rotate the first bridging driven shaft 1095and the second bridging driven shaft 1038. For example, as the electricmotor 1004 operates and causes the second belt 1050 to rotate, thesecond belt 1050 may cause the third right angle gear 1048 to rotate.Rotation of the third right angle gear 1048 may cause the secondbridging shaft 1038 and the second right angle gear 1046 to rotate.Rotation of the second right angle gear 1046 may cause the first belt1047 to rotate, which may cause the first right angle gear 1044 and thefirst bridging driven shaft 1095 to rotate. In some embodiments, agearing ratio between the first right angle gear 1044 and the secondright angle gear 1046 may be approximately 1:1 such that the firstbridging driven shaft 1095 and the second bridging driven shaft 1038 mayrotate at approximately the same speed.

In some embodiments, rotation of the first bridging driven shaft 1095may rotate the first one-way bearings 1091 and the first friction rollerguide 1099, which may be coupled with the first one-way bearings 1091.Similarly, in some embodiments, rotation of the second bridging drivenshaft 1038 may rotate the second one-way bearings 1040 and the secondfriction roller guide 1042, which may be coupled with the second one-waybearings 1040. In some embodiments, rotation of the first and secondfriction roller guides 1099, 1040 may be used to drive rotation of therim 1018 due to friction between the first and second friction rollerguides 1099, 1040 and the interior of the rim 1018. In some embodiments,the second friction roller guide assembly 1036 may be used to increasethe area of contact between the interior of the rim 1018 and the rollerguides in instances where an increased driving friction may be desired.For example, by spreading the driving force over a larger area, thetorque may be increased. Additionally or alternatively, a larger rollerguide may be used with a similar effect. However, a larger roller guidemay introduce a different gear ratio than that experienced by twosmaller roller guides.

Modifications, additions, or omissions may be made to FIGS. 10A and/or10B without departing from the scope of the present disclosure. Forexample, the centerless wheel assembly 1010 may include more or fewerelements than those illustrated and described in the present disclosure.For example, the centerless wheel assembly 1010 may include any numberof friction roller guide assemblies, including less than or more thantwo, as illustrated. As another example, there may be more than onedriving motor (e.g., each of the first and second friction roller guideassemblies 1097, 1036 may be coupled to their own driving motor).

FIG. 11 may illustrate a cutaway view of an example wheel assembly 1110(which may be similar to the wheel assemblies 10, 210, 310, 410, 510,610 a, 610 b, 710, 810, 910, and/or 1010 of FIGS. 1, 2, 3, 4, 5, 6A, 6B,7, 8A, 8B, 9, 10A, and/or 10B). In some embodiments, the wheel assembly1110 may include multiple roller guide assemblies, with, for example, afirst roller guide 1124, a second roller guide 1126, and a third rollerguide 1188. The first roller guide 1124 and the second roller guide 1126may be similar to the first and second roller guides 24, 26 of FIG. 1.The third roller guide 1188 may be similar to the input gear 118 of FIG.8A. The wheel assembly 1110 may also include a first exoskeleton plate1113 and a second exoskeleton plate 1154, which may be similar to thefirst and second exoskeleton plates 13, 54 of FIG. 4, respectively. Thewheel assembly 1110 may additionally include an output gear 1122, whichmay be similar to the output gear 22 of FIG. 8A.

The wheel assembly 1110 may include a centerless rim 1118 thatinterfaces with a tire 1132. The rim 1118 may include a profile withmultiple features for interacting with the roller guides. For example,the rim 1118 may include a first protrusion 1125 sized, shaped, and/orconfigured to interface with the first roller guide 1124 and a secondprotrusion 1127, sized, shaped, and/or configured to interface with thesecond roller guide 1126. The rim 1118 may also include a set of teeth1189 that may function as the output gear 1122 to interface with thethird roller guide 1188, which may be implemented as a toothed gear.

In some embodiments, one or more of the roller guide assemblies of thewheel assembly 1110 may be operably coupled to a driven bridging shaft1195 which may function as an axle for one or more of the roller guideassemblies. In these and other embodiments, one or more of the rollerguide assemblies may be coupled to the driven bridging shaft 1195 suchthat as the driven bridging shaft 1195 rotates, the roller guideassemblies coupled to the driven bridging shaft 1195 also rotate.Additionally or alternatively, one or more of the roller guideassemblies may not be coupled to the driven bridging shaft 1195 and mayspin freely about the driven bridging shaft 1195. For example, in someembodiments the first and/or second roller guides 1124, 1126 may becoupled to one-directional bearings and may be keyed to the drivenbridging shaft 1195. As another example, in some embodiments the firstand/or second roller guides 1124, 1126 may be coupled to free-rollingbearings and may not be keyed to the drive bridging shaft 1195. In someembodiments, the third roller guide 1188 may be a unitary body with thedrive bridging shaft 1195, or may include a gear keyed to the drivebridging shaft 1195.

The drive bridging shaft 1195 maybe operatively coupled to a sprocket,pulley, or right angle gear 1166. The right angle gear 1166 may becoupled (e.g., through a chain, drive shaft, or belt) to a source ofmotive power (e.g., an engine or electric motor such as the motor 104 ofFIG. 8A). As the right angle gear 1166 is rotated, the driven bridgingshaft 1195 may also be rotated. Rotation of the driven bridging shaft1195 may cause any of the roller guide assemblies coupled to the drivenbridging shaft 1195 to rotate as well. Rotation of the driven bridgingshaft 1195 may not cause rotation of any roller guide assemblies notkeyed or otherwise operatively connected to the driven bridging shaft1195. For example, if one of the roller guide assemblies includesfree-rolling bearings, rotation of the driven bridging shaft 1195 maycause the free-rolling bearings to rotate without rotating the rollerguide.

In some embodiments, the wheel assembly 1110 may include multiple rollerguide assemblies that are on different bridging shafts. For example, oneor more of the roller guide assemblies may be disposed on the drivenbridging shaft 1195 and others of the roller guide assemblies may bedisposed on another bridging shaft (not illustrated).

Modifications, additions, or omissions may be made to FIG. 11 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 1110 may include more or fewer elements than thoseillustrated and described in the present disclosure. For example, theprofile of the rim 1118 may take any form or shape, for example,including concave rather than convex features for interacting withroller guide assemblies. As another example, the wheel assembly 1110 mayinclude any combination of friction-based and/or toothed-gear basedroller guide assemblies. As an additional example, any number of rollerguide assemblies may be disposed across the profile of the rim 1118 andany number of roller guide assemblies may be disposed across a bridgingshaft.

Wheelchair Embodiments

FIG. 12A illustrates a front view of an example wheelchair 1200, andFIG. 12B illustrates a side view of the wheelchair 1200 of FIG. 12A, inaccordance with at least one embodiment of the present disclosure. Thewheelchair 1200 may include a first wheel assembly 1210 with anassociated first drive mechanism 1212 and a second wheel assembly 1220with an associated second drive mechanism 1222. The wheelchair 1200 mayadditionally include a third wheel assembly 1230, a fourth wheelassembly 1235, and a payload region 1240.

The first wheel assembly 1210 and/or the second wheel assembly 1220 maybe similar or analogous to the wheel assemblies 10, 210, 310, 410, 510,610 a, 610 b, 710, 810, 910, 1010, and/or 1110 of FIGS. 1, 2, 3, 4, 5,6A, 6B, 7, 8A, 8B, 9, 10A, 10B, and/or 11. In some embodiments, thefirst wheel assembly 1210 and the second wheel assembly 1220 may besimilar or identical. In some embodiments, the first and the secondwheel assemblies 1210, 1220 may be mirror images of each other. Forconvenience in discussing operation, relative positions, etc. of thepresent disclosure, the side of the first wheel assembly 1210 facing thepayload region 1240 may be referred to as an inside face, and theopposite side may be referred to as an outside face. Similarly, the sideof the second wheel assembly 1220 facing the payload region 1240 may bereferred to as an inside face and the opposite side may be referred toas an outside face. The operation of the first and second wheelassemblies 1210 and 1220 may be described with greater detail withrespect to FIG. 13.

The first drive mechanism 1212 and the second drive mechanism 1222 maybe similar or identical. In some embodiments, the first and the seconddrive mechanisms 1212, 1222 may be mirror images of each other. Forconvenience, reference will be made to the first drive mechanism 1212with an understanding that the description may be equally applicable tothe second drive mechanism 1222. The first drive mechanism 1212 may beimplemented as a manual drive mechanism (for example, as illustrated inFIGS. 12A and 12B), as a powered drive mechanism (for example, asillustrated in FIG. 17), or both (for example, as illustrated in FIG.18). In some embodiments (for example, as illustrated in FIG. 12B), afirst lever arm 1215 may be coupled to the first drive mechanism 1212with a first end 1216 of the first lever arm 1215 disposed proximate aseat of the payload region 1240 and a second end 1217 coupled to thefirst drive mechanism 1212. The first end 1216 of the first lever arm1215 may include a handle or other feature for a user of the wheelchair1200 to grasp or otherwise interface with the first lever arm 1215 topush or pull the first lever arm 1215, causing the drive mechanism 1212to drive the first wheel assembly 1210. An example of using the leverarm 1215 to drive the drive mechanism 1212 to drive the first wheelassembly 1210 may be discussed below with reference to FIGS. 15A, 15B,and 16.

In some embodiments, the first drive mechanism 1212 and the second drivemechanism 1222 may be operatively coupled to operate at the same speed,or to otherwise work in a cooperative manner (e.g., the first wheelassembly 1210 driven forward while the second wheel assembly 1220 isdriven backward to turn). In some embodiments, the first lever arm 1215may have a generally arced shape that follows the general outercircumference of the first wheel assembly 1210, such as illustrated inFIG. 12B. Additionally or alternatively, the first lever arm 1215 mayfollow a generally straight line from a handle location to the firstdrive mechanism 1212.

In some embodiments, the first drive mechanism 1212 and the second drivemechanism 1222 may operate independently of each other. For example, thefirst drive mechanism 1212 may operate to drive the first wheel assembly1210 without the second drive mechanism 1222 operating to drive thesecond wheel assembly 1220, and vice versa. In these and otherembodiments, the first drive mechanism 1212 and the second drivemechanism 1222 may be configured to operate cooperatively to perform amaneuver in the wheelchair 1200. For example, to turn in a particulardirection, the first drive mechanism 1212 may drive the first wheelassembly 1210 forward and the second drive mechanism 1222 may drive thesecond wheel assembly 1220 backward. An example of using the lever arm1215 to drive the drive mechanism 1212 to drive the first wheel assembly1210 in either a forward or a backward direction may be discussed belowwith reference to FIGS. 15A, 15B and 16.

The third and/or fourth wheel assemblies 1230 and 1235 may include anywheel assembly configured to provide balance, stability, and/or supportto the wheelchair 1200. For example, the third and/or fourth wheelassemblies 1230 and 1235 may include a canister wheel. Additionally oralternatively, the third and/or fourth wheel assemblies 1230 and 1235may be a centerless wheel. In some embodiments, the third and/or fourthwheel assemblies 1230 and 1235 may be disposed generally behind thefirst and second wheel assemblies 1210, 1220. Additionally oralternatively, the third and/or fourth wheel assemblies 1230 and 1235may be disposed generally in front of the first and second wheelassemblies 1210, 1220 (for example, as illustrated in FIG. 12B). Inthese and other embodiments, a distance between the third wheel assembly1230 and the second wheel assembly 1220 may be approximately equal to abetween the fourth wheel assembly 1235 and the first wheel assembly1210.

In some embodiments, the wheelchair 1200 may omit the fourth wheelassembly 1235. In these and other embodiments, the third wheel assembly1230 may be disposed approximately equidistance between the first andsecond wheel assemblies 1210, 1220. Additionally or alternatively, thethird wheel assembly 1230 may be disposed in front of or behind thefirst and second wheel assemblies 1210, 1220.

In some embodiments, the inclusion or exclusion of the fourth wheelassembly and the location of the third and/or fourth wheel assembliesmay depend on the circumstance and/or environment in which thewheelchair 1200 is likely to be used. For example, in hospital use, thewheelchair 1200 may include the fourth wheel assembly and the third andfourth wheel assemblies may be disposed in front or in back with arelatively short wheel base (e.g., the third and fourth wheel assembliesare within approximately eighteen to forty inches of the first andsecond wheel assemblies 1210, 1220, including approximately twenty fourinches). As another example, for off-road use, the wheelchair 1200 maynot include the fourth wheel assembly and the third wheel assembly 1230may be disposed on an arm of the wheelchair with a longer wheel base(e.g., the third wheel assembly 1230 may be at least withinapproximately twenty four to forty eight inches of the first and secondwheel assemblies 1210, 1220, including approximately thirty six inches).In some embodiments, the third wheel assembly 1230 may be a casterwheel.

The payload region 1240 may include any space, region, or area in whicha payload may be disposed. In some embodiments, the payload region 1240may include a sitting area with a seat, back, arm rest, and/or foot restwhere a user of the wheelchair 1200 may sit when operating thewheelchair 1200. In some embodiments, the payload region 1240 may alsoinclude a storage compartment 1242 or region for stowing of goods ormaterials, (e.g., goods that a user of the wheelchair 1200 desires totransport, and/or motors, batteries, etc. or other components that mayfacilitate the operation of the wheelchair 1200).

Modifications, additions, or omissions may be made to FIGS. 12A and/or12B without departing from the scope of the present disclosure. Forexample, the wheelchair 1200 may include more or fewer elements thanthose illustrated and described in the present disclosure. For example,the wheelchair 1200 may include a fourth wheel assembly. As anotherexample, the wheelchair 1200 may include a motor and/or a battery. As anadditional example, the seat and back illustrated are only examples andthe sitting area may take any form factor.

FIG. 13 illustrates a side cutaway view of an example wheel assembly1300 of a wheelchair in accordance with at least one embodiment of thepresent disclosure. The wheel assembly 1300 may be similar or analogousto the wheel assemblies 10, 210, 310, 410, 510, 610 a, 610 b, 710, 810,910, 1010, and/or 1110 of FIGS. 1, 2, 3, 4, 5, 6A, 6B, 7, 8A, 8B, 9,10A, 10B, and/or 11. In some embodiments, the wheel assembly 1300 may beused for the wheel assembly 1210 or the wheel assembly 1220 describedabove with respect to FIGS. 12A and 12B. The view of the wheel assembly1300 illustrated in FIG. 13 is with respect to looking at an inside faceof the wheel assembly 1300.

The wheel assembly 1300 may include a first roller guide assembly 1310that may be driven, a second roller guide assembly 1320, a third rollerguide assembly 1330, and a fourth roller guide assembly 1340. The wheelassembly 1300 may also include a tire 1332 (which may be similar oranalogous to the tire 32 of FIG. 1), a centerless rim 1318 (which may besimilar or analogous to the centerless rim 18 of FIG. 1), and an outsideface exoskeleton plate 1313 (which may be similar or identical to theexoskeleton plate 13 of FIG. 1).

The first roller guide assembly 1310 may include a roller guide 1324shaped and sized to interface with and roll along the centerless rim1318. The first roller guide assembly 1310 may also include a bridgingshaft 1350 that may function as an axle for the roller guide 1324. Thebridging shaft 1350 may be keyed such that as the bridging shaft 1350 isrotated, the roller guide 1324 may also rotate a corresponding amount.The bridging shaft 1350 may be coupled to a driving mechanism (e.g., thefirst driving mechanism 1212 of FIGS. 12A-12C). The first roller guideassembly 1310 may be similar or analogous to the first friction rollerguide assembly 597 of FIG. 5. For example, the first roller guideassembly 1310 may include bearings and a key. As another example, staticfriction between the roller guide 1324 and the centerless rim 1318 maycause rotation of the roller guide 1324 to rotate the centerless rim1318 and thus drive the wheel assembly 1300.

The second roller guide assembly 1320 and the third roller guideassembly 1330 may be similar or analogous to the first roller guideassembly 14 and/or the second roller guide assembly 16 of FIG. 1. Forexample, the second and third roller guide assemblies 1320, 1330 may beconfigured to roll along the centerless rim 1318 during normaloperation.

The fourth roller guide assembly 1340 may be similar or analogous to thefirst limiter 28 of FIG. 1. For example, the fourth roller guideassembly 1340 may be spaced apart from an interior circumference or edgeof the rim 1318 by a gap. For example, there may be a gap ofapproximately at least one, two, three, four, five, ten, fifteen, etc.thousandths of an inch. The gap may be reduced or eliminated in responseto the wheel assembly 1300 experiencing a drop from an elevation and/ora compression due to a great force or impact such as, for example, anabrupt or sudden stop. The fourth roller guide assembly 1340 may contactthe centerless rim 1318 in response to the drop and/or the compression,which may mitigate effects of the drop and/or the compression.

The wheel assembly 1300 may also include a brake mechanism 1341. Thebrake mechanism 1341 may include any feature, component, or combinationthereof configured to slow, stop, or prevent the rotation of the tire1332. For example, the brake mechanism 1341 may include a brake shoecoupled to at least one of the exoskeleton plates (e.g., the exoskeletonplate 1313 or the corresponding exoskeleton plate not illustrated) andpositioned such that as the brake mechanism 1341 is engaged, the brakeshoe contacts the centerless rim 1318. As another example, the brakemechanism 1341 may include a physical stop coupled at least one of theexoskeleton plates (e.g., the exoskeleton plate 1313 or thecorresponding exoskeleton plate not illustrated) and positioned toengage the tire 1332 to prevent it from rotating relative to theexoskeleton plate 1313 or the corresponding exoskeleton plate notillustrated. Additionally or alternatively, hand rails (e.g., asillustrated and discussed in FIG. 22) may also be utilized as a brakingmechanism by a user of a wheelchair.

In some embodiments, using an analogy of the inside face of the wheelassembly 1300 as a clock, the first roller guide 1310 may be disposed ata six o'clock position, the second roller guide assembly 1320 may be ata seven o'clock position, the third roller guide assembly 1330 may be ata five o'clock position, and the fourth roller guide assembly 1340 maybe at a twelve o'clock position. In some embodiments, the second andthird roller guide assemblies 1320, 1330 may be disposed generallysymmetrically about the location of the first roller guide assembly1310. For example, an angle between the second roller guide assembly1320 and the third roller guide assembly 1330 with reference to a centerof the centerless rim 1318 may include between ten degrees and onehundred and forty degrees and generally symmetric about the six o'clockposition. In some embodiments, the first roller guide assembly 1310 maybe disposed at other locations, for example, between an eight o'clockposition and a four o'clock position. Additionally or alternatively, thefourth roller guide assembly 1340 may be disposed at other locations,for example, between a ten o'clock position and a two o'clock position.

In some embodiments, the wheel assembly 1300 may include a first leverarm 1333 and an associated first spring 1335 and first pivot point 1337.As described above with respect to FIG. 1, the first spring 1335 maybias the fourth roller guide assembly 1340 towards the centerless rim1318, and the first lever arm 1333 may be used to pivot about the firstpivot point 1337 to overcome the spring force of the first spring 1335to remove the tire 1332 and the centerless rim 1318 from the wheelassembly 1300.

In some embodiments, the wheel assembly 1300 may include an anti-tippingfeature, for example, to prevent a user of the wheelchair from tippingover backwards while using the wheelchair. The anti-tipping feature mayinclude a fifth roller guide assembly 1360, a second lever arm 1363, asecond spring 1365, a second pivot point 1367, and a brake block 1369.In operation, when a user of the wheelchair tips backwards, the centerof gravity of the person goes back beyond the roller guide 1324. As thecenter of gravity goes beyond the roller guide 1324, the spring force ofthe first spring 1335 may pull the exoskeleton plate 1313 around,contracting the first spring 1335. Such a spring force may be strongerand counteract the spring force of the second spring 1365. As theexoskeleton plate 1313 is rotated around, the second lever arm 1363rotates about the pivot point 1367 and moves the fifth roller guide 1360into contact with the centerless rim 1318. As the user of the wheelchaircontinues to rotate backwards, further moving the center of gravity offof the roller guide 1324, the fifth roller guide assembly 1360 continuesto move until it abuts against the brake block 1369, at which point theperson in the wheelchair may be prevented from tipping backwards anyfurther. In some embodiments, the material of the fifth roller guideassembly 1360 may be selected to increase friction between the rollerguide and the centerless rim 1318. For example, the roller guide may bemade of a polyurethane or other polymer.

Modifications, additions, or omissions may be made to FIG. 13 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 1300 may include more or fewer elements than thoseillustrated and described in the present disclosure. For example, thewheel assembly 1300 may include fewer roller guide assemblies (e.g.,three instead of four) or additional roller guide assemblies. As anotherexample, the roller guide assemblies may be located and/or spaced apartin any configuration about the wheel assembly 1300 and proximate thecenterless rim 1318.

FIGS. 14A-14D may illustrate embodiments of the present disclosure inwhich a camber angle of the wheel assembly may be modified. FIG. 14Aillustrates an embodiment with a camber angle of approximately zero,FIG. 14B illustrates an example of a negative camber angle, FIG. 14Cillustrates an example of a positive camber angle, and FIG. 14Dillustrates an additional embodiment of negative camber angle.

FIG. 14A illustrates a front view of an example wheel assembly 1410 of awheelchair 1400 in a first position in accordance with at least oneembodiment of the present disclosure. The wheel assembly 1410 may besimilar or analogous to the first wheel assembly 1210 of FIG. 12.Additionally or alternatively, the wheelchair 1400 may be similar oranalogous to the wheelchair 1200 of FIG. 12. The wheelchair 1400 mayinclude a first horizontal strut 1430, a second horizontal strut 1440,and a third horizontal strut 1450. The first horizontal strut 1430 maybe coupled to an inside face exoskeleton plate 1454 via a hinge 1420. Insome embodiments, the horizontal struts (e.g., 1430, 1440, 1450) mayprovide structural support for various components of the wheelchair1400, such as a seat, a footboard, a storage compartment, etc.

The hinge 1420 may include any device, component, or mechanical featureconfigured to allow the first horizontal strut 1430 to interface withthe exoskeleton plate 1454 while maintaining substantially the sameorientation with respect to the ground. For example, the firsthorizontal strut 1430 may remain generally parallel with the ground asthe camber angle of the wheel assembly 1410 is modified because of thehinge 1420. For example, the hinge 1420 may include a mechanicalcomponent to allow the angle of the wheel assembly 1410 to changerelative to the ground while remaining coupled to the first horizontalstrut 1430 and the exoskeleton plate 1454 and maintaining the firsthorizontal strut 1430 in an original orientation with respect to theground. The hinge 1420 may be implemented as a flag hinge, a barrelhinge, a butt/mortise hinge, a continuous hinge, a concealed hinge, abutterfly hinge, a strap hinge, an “H” hinge, a tee hinge, a coachhinge, a flush hinge, etc. Additionally or alternatively, the hinge 1420may be implemented as a ball joint or other spherical bearingconnection. In some embodiments, the second horizontal strut 1440 andthe third horizontal strut 1450 may be coupled to the exoskeleton plate1454 via a hinge (such as the hinge 1420). In some embodiments, thehinge 1420 may be lockable at a target angle. In some embodiments, anyof the first, second, or third horizontal struts 1430, 1440, 1450 may becoupled to the exoskeleton plate 1454 via spring-loaded quick releasepins or similar features that may allow rapid disassembly or adjustmentof the wheelchair, with or without tools.

The first position of the first wheel assembly 1410 may includeapproximately a zero degree camber angle. In some embodiments, the firsthorizontal strut 1430 may have a fixed length. At a zero camber degree,the hinge 1420 may be locked in a partially opened position, such asapproximately a ninety degree bend in the hinge. In some embodiments,the second and/or the third horizontal struts 1440, 1450 may have atelescoping feature such that as the camber angle is adjusted, thelength of the second and/or third horizontal struts 1440, 1450 areadjusted as the first horizontal strut 1430 remains a fixed length.Additionally or alternatively, the second horizontal strut 1440 may havea fixed length and the first and third horizontal struts 1430, 1450 mayinclude a telescoping feature.

FIG. 14B illustrates a front view of the example wheel assembly 1410 ofthe wheelchair 1400 in a second position in accordance with at least oneembodiment of the present disclosure. The second position as illustratedin FIG. 14B illustrates a negative camber angle.

In some embodiments, as the wheel assembly 1410 changes camber angle,the hinge 1420 may rotate such that the first horizontal strut 1430 maymaintain its orientation with respect to the ground, such as generallyparallel with the ground. In addition, the second horizontal strut 1440and the third horizontal strut 1450 may also maintain their orientationwith respect to the ground, such as generally parallel with the ground.In these and other embodiments, the first horizontal strut 1430 maymaintain a fixed length while the second and third horizontal struts1440, 1450 may telescope such that the camber angle of the wheelassembly 1410 changes and the struts maintain their orientation. Forexample, the second horizontal strut 1440 may shorten a first amount,and the third horizontal strut 1450 may shorten a second amount that isshorter than the first amount that the second horizontal strut 1440telescoped.

FIG. 14C illustrates a front view of the example wheel assembly 1410 ofthe wheelchair 1400 in a third position in accordance with at least oneembodiment of the present disclosure. The third position as illustratedin FIG. 14C illustrates a positive camber angle.

In some embodiments, as the wheel assembly 1410 changes camber angle,the hinge 1420 may rotate such that the first horizontal strut 1430 maymaintain its orientation with respect to the ground, such as generallyparallel with the ground. In addition, the second horizontal strut 1440and the third horizontal strut 1450 may also maintain their orientationwith respect to the ground, such as generally parallel with the ground.In these and other embodiments, the first horizontal strut 1430 maymaintain a fixed length while the second figure and third horizontalstruts 1440, 1450 may telescope such that the camber angle of the wheelassembly 1410 changes and the struts maintain their orientation. Forexample, the second horizontal strut 1440 may lengthen a first amount,and the third horizontal strut 1450 may lengthen a second amount that islonger than the first amount that the second horizontal strut 1440telescoped.

FIG. 14D illustrates a front view of the example wheelchair 1400 inaccordance with at least one embodiment of the present disclosure. Thewheelchair 1400 may include a first wheel assembly 1410 a and a secondwheel assembly 1410 b. As illustrated in FIG. 14D, both the first andsecond wheel assemblies 1410 a, 1410 b may include a negative camberangle. In these and other embodiments, the first, second, and thirdhorizontal struts 1430, 1440, and 1450 may generally maintain theirorientation with respect to the ground, such as generally parallel withthe ground. The first horizontal strut 1430 may be coupled to a firstinside exoskeleton plate 1454 a of the first wheel assembly 1410 a via afirst hinge 1420 a and may be coupled to a second inside exoskeletonplate 1454 b of the second wheel assembly 1410 b via a second hinge 1420b. In these and other embodiments, the second and third horizontalstruts 1440, 1450 may be coupled to the first exoskeleton plate 1454 aand the second exoskeleton plate 1454 b, via hinges, ball joints, etc.

In some embodiments, the wheel assemblies may be configured to fold upfor storage or transportation. For example, all but one of thehorizontal struts (e.g., all but the first horizontal strut 1430) may beconfigured to be disengaged from the first exoskeleton plate 1454 a andthe first wheel assembly 1410 a may be configured to rotate towards apositive camber angle for approximately ninety degrees, or even further,such as approximately one hundred and ten or one hundred and twentydegrees.

Additionally or alternatively, all but one of the horizontal struts(e.g., the first horizontal strut 1430) may be disengaged from thesecond exoskeleton plate 1454 b and the second wheel assembly 1410 b maybe configured to rotate towards a positive camber angle forapproximately ninety degrees, or even further, such as approximately onehundred and ten or one hundred and twenty degrees. In these and otherembodiments, interference of the second wheel assembly 1410 b with thefirst wheel assembly 1410 a may limit the rotation of the second wheelassembly 1410 b. For example, the first wheel assembly 1410 a may rotateapproximately ninety degrees such that it is approximately parallel withthe ground, and the second wheel assembly 1410 b may rotateapproximately eighty degrees rather than ninety degrees because ofinterference with the first wheel assembly 1410 a.

Modifications, additions, or omissions may be made to any of FIGS.14A-14D without departing from the scope of the present disclosure. Forexample, the wheelchair 1400 may include more or fewer elements thanthose illustrated and described in the present disclosure. For example,the wheel assembly 1410 may be configured to adjust across a wide rangeof camber angles, positive or negative. For example, the wheel assembly1410 may be adjustable from approximately negative forty degrees camberto approximately positive forty degrees camber (−40° to 40°). As anadditional example, any mechanical joint that allows motion about thejoint may be used in place of the hinge 1420 or at any of the otherinterfaces with the horizontal struts. As an additional example, theremay be more than three horizontal struts (e.g., four, five, six, etc.)and there may be fewer than three horizontal struts (e.g., two or one).

FIGS. 15A and 15B illustrate an example wheel assembly 1500 andassociated drive mechanism 1510 of a wheelchair (e.g., the wheelchair1200 of FIGS. 12A and 12B) in accordance with at least one embodiment ofthe present disclosure. FIG. 15A illustrates the wheel assembly 1500with a lever arm 1520 in a first position and FIG. 15B illustrates thelever arm 1520 in a second position. The wheel assembly 1500 may besimilar or analogous to 10, 210, 310, 410, 510, 610 a, 610 b, 710, 810,910, 1010, 1110, 1300, and/or 1410 of FIGS. 1, 2, 3, 4, 5, 6A, 6B, 7,8A, 8B, 9, 10A, 10B, 11, 13, and/or 14A-D.

In some embodiments, the wheel assembly 1500 may include a drivemechanism 1510 that may be coupled to a lever arm 1520. In particular,the drive mechanism 1510 may include a ratchet mechanism 1530 that maybe coupled to a first end 1521 of the lever arm 1520. The ratchetmechanism 1530 may be coupled to a planetary gear 1540 that may also beincluded with the drive mechanism 1510. The planetary gear 1540 may becoupled to a drive roller 1545 (which may be similar or analogous to thefirst roller guide assembly 1310 of FIG. 13) of the wheel assembly 1500.The lever arm 1520 may be used to provide manual power to drive thewheelchair. The drive mechanism 1510 may convert the manual power fromthe lever arm 1520 into a rotational force to drive the drive roller1545, thereby driving a wheel 1532 of the wheelchair. The ratchetmechanism 1530 may be used to provide manual power from the lever arm1520 to the drive mechanism 1510 when moved in a first direction, whileallowing the lever arm 1520 to return to an original position withoutturning the drive mechanism 1510 in the other direction.

In some embodiments, the drive mechanism 1510 and the lever arm 1520 maybe disposed proximate an inside face of the wheel assembly 1500 suchthat at least a portion of the lever arm 1520 may be disposed betweenthe wheel assembly 1500 and a payload region of the correspondingwheelchair. Additionally or alternatively, in some embodiments, thelever arm 1520 may have a generally arced shape that follows the generalouter circumference of the first wheel assembly 1210 towards the frontof the wheel chair (e.g., the direction a user of the wheelchair isfacing when sitting in the wheelchair). In some embodiments, the leverarm 1520 may have a first position that may be a starting position asillustrated in FIG. 15, with the top of the lever arm 1520 approximatelyhalf way between a twelve o'clock position and a nine o'clock position.

In some embodiments, as the lever arm 1520 is rotated from the firstposition to a second position (such as that illustrated in FIG. 15 B),the ratchet mechanism 1530 may drive the planetary gear 1540. Forexample, the lever arm 1520 may be coupled to the ratchet mechanism 1530such that as the lever arm 1520 is pushed by a user of the wheelchairtowards the front of the wheelchair (e.g., from the first position tothe second position), the ratchet mechanism 1530 may be engaged suchthat the ratchet mechanism 1530 rotates with the lever arm 1520. Theratchet mechanism 1530 may be coupled to the planetary gear 1540 suchthat the rotation of the ratchet mechanism 1530 may cause the planetarygear 1540 to rotate. In these and other embodiments, rotation of theplanetary gear 1540 may drive a roller guide to rotate a wheel 1532 ofthe wheel assembly 1500.

In addition, the ratchet mechanism 1530 may be configured such that asthe lever arm 1520 is pulled back towards the first position from thesecond position (e.g., starting as shown in FIG. 15B), the ratchetmechanism 1530 may allow the lever arm 1520 to rotate back to the firstposition (e.g., ending as shown in FIG. 15A). The ratchet mechanism 1530may also be configured such that the ratchet mechanism 1530 may notengage the planetary gear 1540 as the lever arm 1520 is moving in thedirection from the second position toward the first position such thatthe ratchet mechanism 1530 may not cause the planetary gear 1540 torotate. As such, the ratchet mechanism 1530 may allow for use of thelever arm 1520 in propelling the corresponding wheelchair. One exampleof such a ratchet mechanism may include a one-way bearing system. A setof bearings may be disposed about a member of the lever arm 1520engaging with the planetary gear 1540. As the lever arm 1520 is rotatedfrom the first position to the second position, the bearings lock thelever arm 1520 with the planetary gear 1540 such that movement of thelever arm 1520 also causes movement of the planetary gear 1540. As thelever arm 1520 is rotated from the second position to the firstposition, the bearings disengage so that the lever arm 1520 movesindependently of the planetary gear 1540. Any ratchet mechanism may beused within the scope of the present disclosure.

In some embodiments, the wheelchair may include a feature to reverse thedirection of the ratchet mechanism 1530, such as a cable 1550. Forexample, by squeezing a handle 1555, the cable may be pulled to reversethe direction of the ratchet mechanism 1530. If the cable 1550 isengaged to reverse the direction of the ratchet mechanism 1530, as thelever arm 1520 is pulled from the first position (e.g., starting asshown in FIG. 15A), the ratchet mechanism 1530 may allow the lever arm1520 to rotate to the second position (e.g., finishing as shown in FIG.15B) and the ratchet mechanism 1530 may be configured such that theratchet mechanism 1530 may not engage the planetary gear 1540 as thelever arm 1520 is moving in the direction from the first position towardthe second position such that the ratchet mechanism 1530 may not causethe planetary gear 1540 to rotate. The ratchet mechanism 1530 may befurther configured that as the ratchet mechanism 1530 is moved from thesecond position (e.g., starting as shown in FIG. 15B) to the firstposition (e.g., ending as shown in FIG. 15A), the ratchet mechanism mayengage the planetary gear 1540 such that the ratchet mechanism 1530 maycause the planetary gear 1540 to rotate as the lever arm 1520 is movingin the direction from the second position to the first position. Assuch, the ratchet mechanism 1530 in the reverse direction may allow foruse of the lever arm 1520 in propelling the corresponding wheelchair ina reverse direction. When, the ratchet mechanism 1530 is operating in areverse direction configuration, the planetary gear 1540 may rotate in areverse direction such that the driven roller guide 1545 and the wheel1532 may be propelled in the reverse direction as well.

Modifications, additions, or omissions may be made to FIGS. 15A and 15Bwithout departing from the scope of the present disclosure. For example,the wheel assembly 1500 and the associated drive mechanism 1510 mayinclude more or fewer elements than those illustrated and described inthe present disclosure. For example, the drive mechanism 1510 mayinclude any number of gears, connections, or other mechanical jointswhen transferring the motion of the lever arm 1520 to driving of theroller guide assembly. As an additional example, the lever arm 1520 maytake any shape or form, such as a straight lever from the startingposition to the ratchet mechanism 1530.

FIG. 16 illustrates a view of an example drive mechanism 1600 of awheelchair (e.g., the wheelchair 1200 of FIGS. 12A and 12B) inaccordance with at least one embodiment of the present disclosure. Thedrive mechanism 1600 may be coupled to a lever arm 1620 (which may besimilar or analogous to the lever arm 1520 of FIGS. 15A and 15B) thatmay be coupled to a ratchet mechanism 1630 (which may be similar oranalogous to the ratchet mechanism 1530 of FIGS. 15A and 15B). Theratchet mechanism 1630 may be coupled to a planetary gear 1640 (whichmay be similar or analogous to the planetary gear 1540 of FIGS. 15A and15B). The planetary gear 1640 may be coupled to a drive roller 1624 of awheel assembly.

As described with similar components in FIGS. 15A and 15B, as the leverarm 1620 is rotated, the ratchet mechanism 1630 may also rotate, causingthe planetary gear 1640 to rotate. Rotation of the planetary gear 1640may rotate the drive roller 1624. Static friction between the driveroller 1624 and a rim of the wheel assembly may rotate the rim such thatrotation of drive roller 1624 may cause the wheel assembly to roll alongthe ground. Thus, by using the lever arm 1620, the wheel assembly mayroll along the ground.

Modifications, additions, or omissions may be made to FIG. 16 withoutdeparting from the scope of the present disclosure. For example, thedrive mechanism 1600 and associated drive roller 1624 may include moreor fewer elements than those illustrated and described in the presentdisclosure. For example, the drive mechanism 1600 may include any numberof gears, connections, or other mechanical joints when transferring themotion of the lever arm 1620 to driving of the drive roller 1624. As anadditional example, the lever arm 1620 may take any shape or form, suchas a straight lever from the starting position to the ratchet mechanism1630.

FIG. 17 illustrates an example wheel assembly 1700 and associated drivemechanism of a wheelchair in accordance with at least one embodiment ofthe present disclosure. The wheel assembly 1700 may be similar oranalogous to 10, 210, 310, 410, 510, 610 a, 610 b, 710, 810, 910, 1010,1110, 1300, 1410, and/or 1500 of FIGS. 1, 2, 3, 4, 5, 6A, 6B, 7, 8A, 8B,9, 10A, 10B, 11, 13, 14A-D, and/or 15. The wheel assembly 1700 mayinclude a tire 1732 (which may be analogous to the tire 32 of FIG. 1), acenterless rim 1718 (which may be analogous to the centerless rim 18 ofFIG. 1), and an exoskeleton plate 1713 (which may be analogous to theexoskeleton plate 13 of FIG. 1). The wheel assembly 1700 may include aroller guide assembly 1710 (which may be similar or analogous to thefirst friction roller guide assembly 597 of FIG. 5).

In some embodiments, the wheel assembly 1700 may include an engine or amotor 1720 with an output shaft coupled to a first output gear 1730(e.g., a sprocket, pulley, right-angle gear, etc.). In some embodiments,the output gear 1730 may be coupled with a chain, drive shaft, or belt1740, which may be operably coupled with a second output gear 1750(e.g., a sprocket, pulley, right-angle gear, etc.). For example, thefirst output gear 1730 may be configured to provide an engaging memberto output motive force of the motor 1720. The belt 1740 may be coupledto the first output gear 1730 to change the location of the outputmotive force of the motor 1720 such that as the belt is drawn around thefirst output gear 1730, a corresponding movement is experienced at theopposite end of the belt. The second output gear 1750 may be configuredto apply the motive force from the belt to the location of the secondoutput gear 1750. In some embodiments, the second output gear 1750 maybe operably coupled with a bridging shaft, such as, for example, abridging driven shaft of the roller guide assembly 1710 (which may besimilar or analogous to the bridging driven shaft 695 of the firstfriction roller guide assembly 697 a of FIG. 6A).

In some embodiments, as the motor 1720 drives the first right-angle gear1730, it may rotate the belt 1740. Rotation of the belt 1740 may causethe second right-angle gear 1750 to rotate. Rotation of the secondright-angle gear 1750 may drive the roller guide assembly 1710. In theseand other embodiments, motive force of the motor 1720 may drive theroller guide assembly 1710 such that a roller guide of the roller guideassembly may roll along the centerless rim 1718. For example, staticfriction between the roller guide of the assembly 1710 and thecenterless rim 1718 may facilitate rotation of the roller guide causinga corresponding rotation of the centerless rim 1718, which may drive thewheel assembly 1700.

In some embodiments, a control may be provided to a user of thewheelchair such that as the user operates the control, the speed and/ordirection of the motor 1720 may be varied. For example, the user may beprovided with a joystick control, a series of buttons with directionsand/or speeds, a touch screen control interface, voice-activatedcontrols, a brain to computer interface, etc. Additionally oralternatively, the user may be provided with controls as described withrespect to FIGS. 23A-23C.

Modifications, additions, or omissions may be made to FIG. 17 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 1700 may include more or fewer elements than thoseillustrated and described in the present disclosure. For example, thewheel assembly 1700 may include any number of gears, connections, orother mechanical joints when transferring the motive force of the motor1720 to driving of the roller guide assembly 1710. As an additionalexample, any number of motors or engines may be used to drive the rollerguide assembly 1710. As an additional example, a fuel source, batterypack, etc. may also be included in the wheel assembly 1700 to power theengine or motor 1720.

FIG. 18 illustrates an example wheel assembly 1800 and associated drivemechanism 1810 of a wheelchair in accordance with at least oneembodiment of the present disclosure. In particular, FIG. 18 illustratesa hybrid system including both a manual portion of the drive mechanism1810 (for example, as illustrated in FIGS. 15A and 15B) and a poweredportion of the drive mechanism 1810 (for example, as illustrated in FIG.17). The wheel assembly 1800 may be similar or analogous to the wheelassemblies 10, 210, 310, 410, 510, 610 a, 610 b, 710, 810, 910, 1010,1110, 1300, 1410, 1500, and/or 1700 of FIGS. 1, 2, 3, 4, 5, 6A, 6B, 7,8A, 8B, 9, 10A, 10B, 11, 13, 14A-D, 15A and 15B, and/or 17.

The manual portion of the drive mechanism 1810 may include a lever arm1820 (which may be similar or analogous to the lever arm 1520 of FIGS.15A and 15B). The lever arm 1820 may be coupled to a ratchet mechanism1830 (which may be similar or analogous to the ratchet mechanism 1530 ofFIGS. 15A and 15B). The ratchet mechanism 1830 may be coupled to aplanetary gear 1840 (which may be similar or analogous to the planetarygear 1540 of FIGS. 15A and 15B). In these and other embodiments, thedrive mechanism 1810 may include a cable 1850 for reversing thedirection of the ratchet mechanism 1830 (which may be similar oranalogous to the cable 1550 of FIGS. 15A and 15B).

The powered portion of the drive mechanism 1810 may include a motor 1860(which may be similar or analogous to the motor 1720 of FIG. 17). Anoutput shaft of the motor 1860 may be coupled to a first sprocket, firstpulley, or first right-angle gear 1870 (which may be similar oranalogous to the first right-angle gear 1730 of FIG. 17). In someembodiments, the first right-angle gear 1870 may be coupled with achain, drive shaft, or belt 1880 (which may be similar or analogous tothe belt 1740 of FIG. 17). The belt 1880 may be operably coupled withthe planetary gear 1840 and/or the ratchet mechanism 1830.

In some embodiments, a gear of the planetary gear 1840 to which theratchet mechanism 1830 is coupled may have a width sufficient such thatthe belt 1880 may also be coupled with the same gear of the planetarygear 1840. For example, the ratchet mechanism 1830 may couple with afirst end of the gear of the planetary gear 1840, and the belt 1880 maygo around a middle portion of the gear of the planetary gear 1840, andthe planetary gear 1840 may be configured with a sufficient width toallow both couplings.

In some embodiments, manual driving of the wheel assembly 1800 via thelever arm 1820 may be supplemented by the motive force of the motor1860. For example, the motor 1860 may stop operating while the lever arm1820 is driving the roller guide assembly, but as the lever arm 1820 isbeing rotated back towards a starting position and no longer driving theroller guide assembly, the motor 1860 may engage and continue to drivethe roller guide assembly. As another example, the motor 1860 mayprovide additional torque to the planetary gear 1840, which may make iteasier for a user of the wheelchair to push the lever arm 1820. In theseand other embodiments, controls such as a potentiometer may be coupledto the motor 1860 to control the amount of driving power that may beoutput by the motor 1860. The potentiometer may be controlled oradjusted independently to compensate for physical or neurologicaldisabilities. For example, for a person suffering from tremors,hemispherical paralysis, etc., directional control may be compensatedfor independently by the potentiometer for one or more sides of thewheelchair. In these and other embodiments, the potentiometer may becontrolled via an on-board device, software, or controller, or via aremote device or server (e.g., a cloud-based control system).

Modifications, additions, or omissions may be made to FIG. 18 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 1800 may include more or fewer elements than thoseillustrated and described in the present disclosure. For example, thedrive mechanism 1810 may include any number of gears, connections, orother mechanical joints when transferring the motive force of the motor1860 to driving of the roller guide assembly. As an additional example,a fuel source, battery pack, etc. may also be included in the wheelassembly 1800 to power the engine or motor 1860. As another example, thedrive mechanism 1810 may include any number of gears, connections, orother mechanical joints when transferring the motion of the lever arm1820 to driving of the roller guide assembly. As an additional example,the lever arm 1820 may take any shape or form, such as a straight leverfrom the starting position to the ratchet mechanism 1830.

FIG. 19 illustrates an exploded view of example wheel assembly 1900 andassociated drive mechanism 1910 of a wheelchair in accordance with atleast one embodiment of the present disclosure. FIG. 19 may be similarto the embodiment illustrated in FIG. 18, but may provide an alternativeview of how various components are connected. In particular, FIG. 19illustrates a hybrid system including both a manual portion of the drivemechanism 1910 (for example, as illustrated in FIG. 15) and a poweredportion of the drive mechanism 1910 (for example, as illustrated in FIG.17). The wheel assembly 1900 may be similar or analogous to the wheelassemblies 10, 210, 310, 410, 510, 610 a, 610 b, 710, 810, 910, 1010,1110, 1300, 1410, 1500, 1700, and/or 1800 of FIGS. 1, 2, 3, 4, 5, 6A,6B, 7, 8A, 8B, 9, 10A, 10B, 11, 13, 14A-D, 15, 17, and/or 18.

The manual portion of the drive mechanism 1910 may include a lever arm1920 (which may be similar or analogous to the lever arm 1520 of FIG.15). The lever arm 1920 may be coupled to a ratchet mechanism 1930(which may be similar or analogous to the ratchet mechanism 1530 of FIG.15). The ratchet mechanism 1930 may be coupled to a planetary gear 1940(which may be similar or analogous to the planetary gear 1540 of FIG.15). The powered portion of the drive mechanism 1910 may include a motor1960 (which may be similar or analogous to the motor 1720 of FIG. 17).An output shaft of the motor 1960 may be coupled to a first sprocket,first pulley, or first right-angle gear 1970 (which may be similar oranalogous to the first right-angle gear 1730 of FIG. 17). In someembodiments, the first right-angle gear 1970 may be coupled with achain, drive shaft, or belt 1980 (which may be similar or analogous tothe belt 1740 of FIG. 17). The belt 1980 may be operably coupled withthe planetary gear 1940. The powered portion of the drive mechanism 1910may also include a mounting bracket 1990 which may support the motor1960 and be coupled to the motor 1960 and an exoskeleton plate of thewheel assembly 1900.

Modifications, additions, or omissions may be made to FIG. 19 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 1900 may include more or fewer elements than thoseillustrated and described in the present disclosure.

FIG. 20 illustrates an exploded view of an example drive mechanism 2000,in accordance with at least one embodiment of the present disclosure.The drive mechanism 2000 may be similar or analogous to the drivemechanism 1810 of FIG. 18 and 1910 of FIG. 19. The operation of thedrive mechanism 2000 may also be similar to the drive mechanism 1810 ofFIG. 18 and 1910 of FIG. 19, and FIG. 20 may be provided to illustratehow various components of the drive mechanism 2000 may be connected.

The drive mechanism 2000 may include an outer casing plug 2005 that maybe coupled to an outer casing 2010 of the ratchet mechanism. The outercasing 2010 may include a gap through which a lever interface component2015 may protrude. A lever arm 2002 (e.g., the lever arms describedabove) may couple with the lever interface component 2015 (e.g., bybeing bolted via bolt 2004 to the lever interface component 2015). Aratchet gear assembly 2020 may be disposed within the lever interfacecomponent 2015 such that rotation of the lever interface component 2015(e.g., through movement of the lever arm) may cause the ratchet outputgear 2025 to rotate. For example, the ratchet gear assembly 2020 mayinclude a one-way bearing system as described with respect to FIGS. 15Aand 15B. Using the ratchet gear assembly 2020, as the lever arm 2002 isrotated in one direction, the ratchet gear assembly 2020 may causerotation of the ratchet output gear 2025 while rotation in an oppositedirection may not cause rotation of the ratchet output gear 2025.

A washer 2030 may be disposed within the lever interface component 2015to lock the lever interface component 2015 and the ratchet gear assembly2020 in relative position with each other. Another outer casing plug2035 may be disposed proximate an output end of the ratchet output gear2025 to enclose the ratchet components (e.g., the ratchet gear assembly2020). The ratchet output gear 2025 may protrude out of the outer casing2010 and interface with a first planetary gear component 2040 such thatrotation of the ratchet output gear 2025 may cause the first planetarygear component 2040 to rotate. The first planetary gear component 2040may be coupled to a second planetary gear component 2045.

The ratchet output gear 2025 may protrude through a central casingmember 2050. The central casing member may interface with the outercasing 2010 of the ratchet mechanism and a slotted casing member 2060.The slotted casing member 2060 may encase the first and second planetarygear components 2040, 2045 and an output axle 2055. The output axle 2055may be coupled to the second planetary gear assembly 2045 as well as amotor interface gear 2065. The motor interface gear 2065 may occupy theslot of the slotted casing member 2060. A belt, chain, or driveshaft mayengage the motor interface gear 2065 through the slot of the slottedcasing member 2060. The slotted casing member may be capped by an insidecasing member 2075 and an inside casing plug 2070. The output axle(coupled to both the second planetary gear component 2040 and the motorinterface gear 2065) may protrude out of the inside casing member 2075to be coupled with a drive roller.

In some embodiments, as the output axle 2055 is rotated, a drive roller(such as the drive rollers described above) may also be caused torotate. In these and other embodiments, the output axle 2055 may bekeyed to facilitate locking with the second planetary gear component2045, the motor interface gear 2065, and/or the drive roller such thatthe components may move as a single body.

Modifications, additions, or omissions may be made to FIG. 20 withoutdeparting from the scope of the present disclosure. For example, thedrive mechanism 2000 may include more or fewer elements than thoseillustrated and described in the present disclosure.

FIG. 21 illustrates an example wheel assembly 2100 in accordance with atleast one embodiment of the present disclosure. FIG. 21 may illustratean alternative configuration of an exoskeleton plate 2113.

The wheel assembly 2100 may be similar or analogous to the wheelassemblies 10, 210, 310, 410, 510, 610 a, 610 b, 710, 810, 910, 1010,1110, 1300, 1410, 1500, 1700, and/or 1800 of FIGS. 1, 2, 3, 4, 5, 6A,6B, 7, 8A, 8B, 9, 10A, 10B, 11, 13, 14A-D, 15, 17, and/or 18. The wheelassembly may include a first roller guide assembly 2110 (which may besimilar or analogous to the first roller guide assembly 1310 of FIG.13), a second roller guide assembly 2120 (which may be similar oranalogous to the second roller guide assembly 1320 of FIG. 13), a thirdroller guide assembly 2130 (which may be similar or analogous to thethird roller guide assembly 1330 of FIG. 13), and a fourth roller guideassembly 2140 (which may be similar or analogous to the fourth rollerguide assembly 1340 of FIG. 13). The wheel assembly 2100 may include atire 2132 (which may be similar or analogous to the tire 32 of FIG. 1)and a centerless rim 2118 (which may be similar or analogous to thecenterless rim 18 of FIG. 1).

As illustrated in FIG. 21, the exoskeleton plate 2113 may be rectangularin shape, including, for example, a square. The exoskeleton plate 2113may take any shape or form that provides support for the roller guideassemblies. For example, the exoskeleton plate 2113 may extend to eachof the areas where a roller guide assembly is located. For example, theexoskeleton plate 2113 extends to cover each of the first, second, thirdand fourth roller guide assemblies 2110, 2120, 2130, 2140. Additionallyor alternatively, the exoskeleton plate 2113 may not extend to aparticular roller guide assembly but may include a support member orother component extending beyond the exoskeleton plate 2113 to providesupport to the particular roller guide. In these and other embodiments,the exoskeleton plate 2113 may be produced from any material, includingwood, metal, plastic, etc.

Modifications, additions, or omissions may be made to FIG. 21 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 2100 may include more or fewer elements than thoseillustrated and described in the present disclosure. As an additionalexample, the exoskeleton plate 2113 may take any shape or form (e.g., anoctagon, a hexagon, an oblong rectangle, an irregular shape, etc.).

FIG. 22 illustrates an example wheel assembly 2200 with an example handrail 2250. The wheel assembly 2200 may be similar or analogous to thewheel assemblies 10, 210, 310, 410, 510, 610 a, 610 b, 710, 810, 910,1010, 1110, 1300, 1410, 1500, 1700, 1800, and/or 2100 of FIGS. 1, 2, 3,4, 5, 6A, 6B, 7, 8A, 8B, 9, 10A, 10B, 11, 13, 14A-D, 15, 17, 18, and/or21. The wheel assembly 2200 may include a tire 2232 (which may besimilar or analogous to the tire 32 of FIG. 1), a centerless rim 2218(which may be similar or analogous to the centerless rim 18 of FIG. 1),and a first exoskeleton plate 2213 (which may be similar or analogous tothe first exoskeleton plate 13 of FIG. 1).

The wheel assembly 2200 may additionally include the hand rail 2250 thatmay be coupled to the centerless rim 2218 such that the hand rail 2250and the tire 2232 may move as a unitary body. Stated another way, amotion or force on the hand rail 2250 may cause a corresponding motionor force on the tire 2232. For example, a user of a wheelchair includingthe wheel assembly 2200 may grasp the hand rail 2250 and turn the handrail 2250, which may in turn cause the tire 2232 to rotate, providing amotive force to the wheelchair.

The hand rail 2250 may be coupled to the centerless rim 2218 along oneside of the centerless rim 2218 via one or more posts 2260 (such as theposts 2260 a-2260 f) (examples of such a coupling are also illustratedin FIGS. 23A-23C). The posts 2260 may be placed at regular intervalsaround the wheel assembly 2200. The posts 2260 may span from the handrail 2250 to the centerless rim 2218 and may be coupled to thecenterless rim 2218. In these and other embodiments, the posts 2260 maybe coupled in such a way and in such a location that the posts 2260 donot cause any interference with any roller guides that may roll alongthe centerless rim 2218.

While only one wheel assembly 2200 is illustrated, it will beappreciated that a wheelchair may include a hand rail (such as the handrail 2250) on both sides of a wheel chair. For example, a wheelchair maybe configured so that a user of the wheelchair may use hand rails onboth sides of the wheelchair to drive the wheelchair.

Modifications, additions, or omissions may be made to FIG. 22 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 2200 may include more or fewer elements than thoseillustrated and described in the present disclosure.

FIGS. 23A, 23B, and 23C illustrate cutaway views of example hand rails2350. In some embodiments, a wheelchair may include a hand control 2370on the handrail 2350 to signal a motor of the wheelchair to providemotive force to the wheelchair. For example, the hand control may causea motor of the wheelchair to drive the wheelchair when a user of thewheelchair activates the hand control 2370.

As illustrated in FIG. 23A, a hand rail 2350 a (which may be similar oranalogous to the handrail 2250 of FIG. 22) may be coupled to acenterless rim 2318 (which may be similar or analogous to the centerlessrim 18 of FIG. 1) via one or more posts 2360 (which may be similar oranalogous to the posts 2260 of FIG. 22). A tire 2332 (which may besimilar or analogous to the tire 32 of FIG. 1) may be coupled to thecenterless rim 2318.

The hand rail 2350 a may include a hand control 2370 a along at least aportion of the hand rail 2350 a. In some embodiments, the hand control2370 a may be offset approximately ninety degrees from the post 2360. Inthese and other embodiments, the hand control 2370 a may include a touchactivated panel or surface, a touch-responsive material, one or moremanual buttons, an electrically conductive panel or surface, anelectrically conductive material, any combinations thereof, etc. In someembodiments, the hand control 2370 a may go along the entirecircumference of the hand rail 2350 a, along a portion of thecircumference of the hand rail 2350 a, or intermittent segments alongthe circumference of the hand rail 2350 a.

For example, as a user of a wheelchair including the hand rail 2350 auses the hand rail 2350 a to provide motive force to the wheelchair, theuser grasping the hand rail 2350 a may invoke the hand control 2370 a.By invoking the hand control 2370 a, the user may cause a motorassociated with the wheelchair to provide motive force to thewheelchair. For example, the motor may be coupled to a drive roller asdescribed and illustrated with respect to FIG. 17.

FIG. 23B may be similar or analogous to FIG. 23A, with a variation inthe placement of the hand control 2370 b on the hand rail 2350 b. FIG.23A includes the hand control 2370 a offset from the post 2360 byroughly ninety degrees. FIG. 23B includes the hand control 2370 b offsetfrom the post 2360 by roughly one hundred and eighty degrees. With theembodiment illustrated in FIG. 23A, a user of a wheelchair may use theirfingers when grasping the hand rail 2350 a to touch, press, or otherwiseinvoke the hand control 2370 a when desired. With the embodimentillustrated in FIG. 23B, a user of the wheelchair may use their palm orfingers to touch, press, or otherwise invoke the hand control 2370 b.Additionally, with the placement of the hand control 2370 b, a user mayto touch, press, or otherwise invoke the hand control 2370 b nearlyevery time the hand rail 2350 b is used.

FIG. 23C may be similar or analogous to FIGS. 23A and 23 b, with avariation in the hand controls 2370 c and 2370 d on the hand rail 2350c. As illustrated in FIG. 23C, in some embodiments the hand rail 2350 cmay include more than one hand control 2370, such as the hand controls2370 c and 2370 d. In these and other embodiments, the hand controls2370 c and 2370 d may operate such that either may activate the motor,or both must be invoked simultaneously to invoke the motor. For example,by including the hand control 2370 c and 2370 d, incidental contact witheither of the touch controls 2370 c and 2370 d may not activate themotor.

In some embodiments, the hand controls 2370 may include a selectivelyresponsive material. For example, the hand controls may only beresponsive to particular materials, such as skin, a particular type ofmetal woven into a glove worn by the user, etc.

The hand controls 2370 may be communicatively coupled with a motorassociated with the wheel of the wheelchair. For example, there may be awired electrical connection from the hand controls 2370 to the motor, orthere may be a wireless connection between the hand controls and/orassociated circuitry and the motor.

Modifications, additions, or omissions may be made to FIGS. 23A, 23B,and 23C without departing from the scope of the present disclosure. Forexample, the embodiments illustrated may include more or fewer elementsthan those illustrated and described in the present disclosure. As anadditional example, the hand rail 2350 may take any shape or profile,and the hand control 2370 may take any shape or profile.

FIG. 24 illustrates an example wheel assembly 2400 with an example handrail 2450 with various sensors. The wheel assembly 2400 may be similaror analogous to the wheel assemblies 10, 210, 310, 410, 510, 610 a, 610b, 710, 810, 910, 1010, 1110, 1300, 1410, 1500, 1700, 1800, 2100, and/or2200 of FIGS. 1, 2, 3, 4, 5, 6A, 6B, 7, 8A, 8B, 9, 10A, 10B, 11, 13,14A-D, 15, 17, 18, 21, and/or 22. The wheel assembly 2400 may include atire 2432 (which may be similar or analogous to the tire 32 of FIG. 1),a centerless rim 2418 (which may be similar or analogous to thecenterless rim 18 of FIG. 1), and a first exoskeleton plate 2413 (whichmay be similar or analogous to the first exoskeleton plate 13 of FIG.1). The hand rail 2450 may be similar or analogous to the hand rail 2250of FIG. 22.

In some embodiments, there may be one or more sensors 2410 disposedalong the hand rail 2450. Additionally or alternatively, there may beone or more sensors 2420 disposed along the first exoskeleton plate2413. The sensors 2410 and the sensors 2420 may include any device,component, or combination thereof configured to sense position,velocity, acceleration, or any combinations thereof. For example, thesensors 2410 and the sensors 2420 may include a capacitive sensor, apotentiometer, a proximity sensor, an inductive sensor, anaccelerometer, a gyroscope, a magnetometer, etc., or any combinationsthereof. In some embodiments, the sensors 2410 and the sensors 2420 maywork together to determine any of position, velocity, and/oracceleration.

In some embodiments, the sensors 2410 and/or the sensors 2420 may beutilized to control the amount of power supplied to a motor associatedwith a wheel of a wheelchair. For example, if the hand rail 2450 isrotated relatively slowly by a user, causing a low acceleration, arelatively low amount of power may be provided to the motor. As anotherexample, if the hand rail 2450 is rotated relatively quickly by a user,causing a larger acceleration, a larger amount of power may be providedto the motor. As another example, more power may be provided by themotor when the wheel 2242 is turning slowly and less power may beprovided by the motor when the wheel 2242 is turning quickly.

Modifications, additions, or omissions may be made to FIG. 24 withoutdeparting from the scope of the present disclosure. For example, thewheel assembly 2400 may include more or fewer elements than thoseillustrated and described in the present disclosure. As another example,only a single sensor on the hand rail 2450, the wheel 2432, or thecenterless rim 2418 may be used to sense any of position, velocity, oracceleration. As an additional example, the control based on the sensorsmay also be coupled to and applied to an electronically controlledbraking system, which may include the motor running in reverse.

Slippage Control

FIG. 25A illustrates an example of a centerless wheel assembly 2510 aable to invoke a corrective action, in accordance with one or moreembodiments of the present disclosure. The centerless wheel assembly2510 a may be similar or comparable to the wheel assembly 710 of FIG. 7,and may illustrate one embodiment of implementing a corrective action inresponse to slippage. The wheel 2532, the rim 2518 and the computingdevice 2545 may be similar or comparable to the wheel 732, the rim 718,and the computing device 745, respectively.

In some embodiments, the roller guide 2599 a may be disposed on anextending device 2520. The extending device 2520 may be in communicationwith the computing device 2545. The computing device 2545 may beconfigured to send signals to cause the extending device 2520 to extendor retract the roller guide 2599 a relative to the rim 2518. Forexample, if slippage is detected, the computing device 2545 may extendthe extending device 2520 towards the rim 2518 such that the rollerguide 2599 a is further compressed against the rim 2518, increasing thelikelihood of the slippage ending. After the slippage has ended, theextending device 2520 may be retracted back to an original position.

The extending device 2520 may include any device or component configuredto mechanically displace the roller guide 2599 a towards and/or awayfrom the rim 2518 in a controlled manner. For example, the extendingdevice 2520 may include one or more spring-loaded pivots, pneumaticarms, telescoping arms, etc. In some embodiments, the extending device2520 may be configured to receive a signal from the computing device2545 and adjust the amount of extension of the extending device 2520based on the signal. For example, the computing device 2545 may monitora variety of sensors of the wheel assembly 2510 a. After detecting thatslippage has occurred (e.g., because the roller guide 2599 a is spinningfaster than normal compared to the speed of the rim 2518), the computingdevice 2545 may send a message to the extending device 2520 to move theroller guide 2599 a closer to the rim 2518 as a corrective action. Forexample, the signal may direct the extending device 2520 to compress aspring, forcing the roller guide 2599 a towards the rim 2518. By forcingthe roller guide 2599 a towards the rim 2518, the roller guide 2599 amay overcome the slippage.

In some embodiments, forcing the roller guide 2599 a towards the rim2518 may be a part of the corrective action. For example, the correctiveaction may include decreasing or removing power to the roller guide 2599a. In these and other embodiments, the combination of decreasing orremoving power in addition to forcing the roller guide 2599 a towardsthe rim 2518 may increase the likelihood of overcoming slippage ascompared to either of the parts of the corrective action on their own.

In some embodiments, the extending device 2520 may be configured toretract the roller guide 2599 a away from the rim 2518. In these andother embodiments, the computing device 2545 may monitor for ending ofslippage after a corrective action has been undertaken (e.g., afterforcing the roller guide 2599 a towards the rim 2518 and/or reducingpower to the roller guide 2599 a). After detecting that slippage hasended (e.g., because the speed of the roller guide 2599 a and the rim2518 are back within normal operating speeds relative to each other),the corrective action may be ended as well. For example, ending thecorrective action may include retracting the extending device 2520 suchthat the roller guide 2599 a moves back away from the rim 2518 to anoriginal position. In these and other embodiments, the roller guide 2599a may continue to maintain contact with the rim 2518 such that theroller guide 2599 a may continue to drive the wheel assembly 2510 a.

FIG. 25B illustrates another example of a centerless wheel assembly 2510b able to invoke a corrective action. The wheel assembly 2510 b mayinclude the tire 2532, the rim 2518, and the computing device 2545 thatmay be the same or comparable to the like-numbered components of FIG.25A. The wheel assembly 2510 b may additionally include a roller guide2599 b that may be similar or comparable to one or more roller guides ofthe present disclosure (e.g., the roller guide 2599 a of FIG. 25A). Thewheel assembly 2510 b may include a pneumatic device 2530 and a hose2535.

As described in the present disclosure, the computing device 2545 maymonitor for conditions indicative of slippage. For example, thecomputing device 2545 may monitor the speed of the roller guide 2599 b,the tire 2532, the rim 2518, another idler roller guide (notillustrated), or any other component of the wheel assembly 2510 b. Inthese and other embodiments, the computing device 2545 may compare thespeed of various components to determine whether or not slippage isoccurring. For example, if the roller guide 2599 b is rotating fasterthan a threshold speed relative to the rim 2518 (e.g., outside of anormal relationship of the two speeds), the computing device 2545 maydetermine that slippage is occurring. After detecting that slippage isoccurring, the computing device 2545 may undertake a corrective action.

In some embodiments, the roller guide 2599 b may be an inflatabledevice, such as a rubber/polymer-based wheel such that as a gas orliquid is added to the roller guide 2599 b, the pressure within theroller guide 2599 b may increase or the size of the roller guide 2599 bmay increase. For example, the pneumatic device 2530 may pump a gasthrough the hose 2535 and into the roller guide 2599 b. As the rollerguide 2599 b increases in pressure, the slippage may be more likely toend. For example, if the roller guide 2599 b is a fixed distance fromthe rim 2518, inflating the roller guide 2599 b may expand the rollerguide 2599 b, forcing the roller guide 2599 b against the rim 2518. Insome embodiments, the pneumatic device 2530 may be in communication withthe computing device 2545 and may be responsive to signals from thecomputing device 2545. For example, the computing device 2545 may detectthat slippage is occurring and may send a signal to the pneumatic device2530 to pump a gas or liquid into the roller guide 2599 b.

In some embodiments, the wheel assembly 2510 b may be configured toreduce, reverse, or stop the corrective after detecting that slippagehas ended. For example, the computing device may detect that slippagehas ended and may send a message to the pneumatic device 2530 towithdraw the gas or liquid through the hose 2535 from the roller guide2599 b.

FIGS. 25A and 25B illustrate two potential embodiments for increasingstatic friction between a roller guide 2599 and the rim 2518 in aneffort to overcome slippage. However, the present disclosurecontemplates any number of alternative approaches to increase the staticfriction between the roller guide 2599 and the rim 2518 to overcomeslippage. Such approaches may include combinations of one or more of theembodiments of the present disclosure.

In some embodiments, a combination of the embodiments of FIGS. 25A and25B may be included in a wheel assembly. For example, the extendingdevice 2520 may be coupled to the roller guide 2599 b that may beinflatable. If the computing device 2545 detects slippage is occurring,the pneumatic device 2530 may withdraw gas or liquid from the rollerguide 2599 b while the extending device 2520 forces the roller guide2599 b towards the rim 2518. Such a combination may cause the rollerguide 2599 b to be more deformable and forced against the rim 2518,effectively increasing the surface area contact between the roller guide2599 b and the rim 2518. In these and other embodiments, such acombination may be further combined with reducing power or speed of theroller guide 2599 b. For example, the computing device 2545 maysimultaneously and in a coordinated manner send a first message to thepneumatic device 2530 to decrease the amount of gas or liquid in theroller guide 2599 b, send a second message to the extending device 2520to force the roller guide 2599 b towards the rim, and send a thirdmessage to a motor driving the roller guide 2599 b (not illustrated) toreduce the speed and/or power applied to the roller guide 2599 b. Afterthe computing device 2545 detects that slippage has ended, the computingdevice 2545 may send a fourth message to the pneumatic device 2530 toincrease the amount of gar or liquid in the roller guide 2599 b to anoriginal amount, a fifth message to the extending device 2520 to retractthe roller guide 2599 b back away from the rim 2518 to an originalposition, and a sixth message to the motor to increase the speed and/orpower applied to the roller guide 2599 b back to an original amount.

Modifications, additions, or omissions may be made to FIGS. 25A and 25Bwithout departing from the scope of the present disclosure. For example,the wheel assemblies 2510 a and/or 2510 b may include more or fewerelements than those illustrated and described in the present disclosure.For example, any combination of features or elements of any of theembodiments of the present disclosure may be included in the wheelassemblies 2510 a and/or 2510 b.

FIG. 26 illustrates a flow chart of an example method 2600 of addressingslippage, in accordance with one or more embodiments of the presentdisclosure. The method 700 may be performed by any suitable system,apparatus, or device. For example, the wheel assembly 710, the computingdevice 745 of FIG. 7, the wheel assemblies 2510 a, 2510 b, and/or thecomputing device 2545 of FIGS. 25A and 25B may perform one or more ofthe operations associated with the method 2600. Although illustratedwith discrete blocks, the steps and operations associated with one ormore of the blocks of the method 2600 may be divided into additionalblocks, combined into fewer blocks, or eliminated, depending on thedesired implementation.

At block 2610, a wheel (e.g., the wheel assembly 710 of FIG. 7) may bedriven by a drive roller guide (e.g., the drive roller guide 799)coupled to a motor (e.g., the motor 704 of FIG. 7). For example, acenterless wheel with a centerless rim may be driven by the drive rollerguide coupled to the motor. In these and other embodiments, the driveroller guide may drive the centerless wheel by the motor impartingmotive force to the drive roller guide, and static friction between thedrive roller guide and the centerless rim causing the centerless rim torotate as the drive roller guide rotates (e.g., the centerless rim mayroll along the drive roller guide). In some embodiments a computingdevice (e.g., the computing device 745 of FIG. 7)

The centerless wheel may include one or more idler roller guides as wellas one or more limiters. Multiple sensors to measure position, velocity,and/or acceleration may be distributed throughout the wheel assembly,for example, as illustrated and described with reference to FIG. 7. Forexample, the motor and/or an output gear of the motor may include asensor, the drive roller guide may include a sensor, the rim may includea sensor, one or more of the idler roller guides may include a sensor,and/or the wheel may include a sensor.

At block 2620, a variety of parameters may be monitored, including motorspeed of the motor, idler roller guide speed of the idler roller guide,and wheel speed of the wheel. For example, the computing device mayreceive or otherwise monitor signals from the multiple sensorsthroughout the wheel assembly. The computing device may monitor thespeed of the various components as RPM, or as some other measure ofspeed.

At block 2630, a determination may be made as to whether slippage isoccurring between the drive roller guide and the centerless rim based ona numerical relationship between the motor speed, the idler roller guidespeed, and/or the wheel speed. For example, the computing device mayhave stored one or more relationships regarding speed among the variouscomponents. For example, without slippage, a certain number of RPMs ofthe drive roller guide would correspond to a certain number of RPMs ofthe centerless rim and/or the wheel. In some embodiments, such arelationship may be based on a gearing ratio of the drive roller guideand the centerless rim. In these and other embodiments, a mismatch inthat relationship may indicate that slippage is occurring. For example,a threshold speed relationship may be stored by the computing device,and if the speed of the drive roller guide exceeds that threshold, thecomputing device may determine that slippage is occurring. If it isdetermined that slippage has occurred or is occurring, the method 2600may proceed to the block 2640. If no slippage has been detected, themethod 2600 may proceed to the block 2650.

While it is the relationship in speed differences between the centerlessrim and the drive roller guide that may indicate slippage, any number ofother components may be utilized to determine whether slippage hasoccurred indirectly. For example, if a drive chain or other componentthat avoids slippage is connecting the motor and the drive roller guide,the speed of the motor may be measured and that speed correlated todetermine the speed of the drive roller. In these and other embodiments,such a relationship may be based on the gearing ratio between the motorand the drive roller guide. In some embodiments, if a belt or otherconnecting drive component couples the motor to the drive roller guide,slippage may be possible between the belt and the drive roller guide andso monitoring the motor speed may be less favorable than measuring thedrive roller guide directly. As another example, the idler roller guidemay roll along the centerless rim, even if the torque applied to thedrive roller guide overcomes the static friction and causes slippage. Inthese and other embodiments, the speed of the idler roller guide may bemonitored to determine the speed of the centerless rim. If the idlerroller guide is the same size as the driver roller guide, such arelationship may be based on the gearing ratio of the drive roller guideand the wheel.

At block 2640, a corrective action may be taken. For example, thecomputing device may send a message to an extending device (e.g., theextending device 2520 of FIG. 25A). As another example, the computingdevice may send a message to a pneumatic device (e.g., the pneumaticdevice of FIG. 25B). As an additional example, the computing device maysend a message to the motor to decrease or remove power to the driveroller guide. In some embodiments, the corrective action may include anycombination of the foregoing, or any other action that may facilitate anincrease in friction between the drive roller guide and the centerlessrim to restore a rolling situation (e.g., to restore static frictionbetween the drive roller guide and the centerless rim such that thedrive roller guide may drive the wheel). In some embodiments, the extentof the corrective action (e.g., the amount of extension, the decrease inpower, the amount of inflation) may be proportional to how far the speedof the drive roller guide exceeded the speed of the centerless rim.After taking the corrective action, the method 2600 may proceed to block2620 to continue to monitor the various speed parameters. If thecomputing device determines that slippage continues to occur, thecorrective action may be extended or enhanced, additional correctiveactions may be taken, etc. For example, the extending device may beextended further if slippage continues to occur.

At block 2650, a determination may be made as to whether a correctiveaction has been taken. For example, if normal operation has occurred andno slippage was occurring at block 2630 and no corrective action hasbeen taken at block 2640, the method 2600 may proceed to block 2620 tocontinue to monitor the various parameters of the wheel assembly. If acorrective action had been taken at the block 2640, and there is nolonger slippage as determined at the block 2630, the method 2600 mayproceed to block 2660. For example, the computing device may have aflag, a bit, or some other storage feature that may track whether acorrective action is currently being used.

At block 2660, the corrective action may be stopped. For example, thecomputing device may lessen, remove, or cease one or more of thecorrective actions that may have been taken. For example, if anextending device had been extended at block 2640, the extending devicemay be retracted to an original position of normal operation at theblock 2660. As another example, if the pneumatic device had inflated theroller guide at block 2640, the pneumatic device may deflate the rollerguide back to an original pressure for normal operation at the block2660. As an additional example, if the computing device had decreased orlimited the power or energy provided to the motor at block 2640, thecomputing device may reinstate normal operating conditions to the motorat the block 2660. Any combination of the foregoing is alsocontemplated, as well as any other corrective action undertaken at theblock 2640.

Modifications, additions, or omissions may be made to the method 2600without departing from the scope of the present disclosure. For example,the operations of the method 2600 may be implemented in differing order.Additionally or alternatively, two or more operations may be performedat the same time. Furthermore, the outlined operations and actions areprovided as examples, and some of the operations and actions may beoptional, combined into fewer operations and actions, or expanded intoadditional operations and actions without detracting from the essence ofthe disclosed embodiments.

Terms used in the present disclosure and especially in the appendedclaims (e.g., bodies of the appended claims) are generally intended as“open” terms (e.g., the term “including” should be interpreted as“including, but not limited to,” the term “having” should be interpretedas “having at least,” the term “includes” should be interpreted as“includes, but is not limited to,” the term “containing” should beinterpreted as “containing, but not limited to,” etc.).

Additionally, if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations.

In addition, even if a specific number of an introduced claim recitationis explicitly recited, those skilled in the art will recognize that suchrecitation should be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, means at least two recitations, or two or more recitations).Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” or “one or more of A, B, and C, etc.” isused, in general such a construction is intended to include A alone, Balone, C alone, A and B together, A and C together, B and C together, orA, B, and C together, etc.

Further, any disjunctive word or phrase presenting two or morealternative terms, whether in the description, claims, or drawings,should be understood to contemplate the possibilities of including oneof the terms, either of the terms, or both terms. For example, thephrase “A or B” should be understood to include the possibilities of “A”or “B” or “A and B.”

All examples and conditional language recited in the present disclosureare intended for pedagogical objects to aid the reader in understandingthe disclosure and the concepts contributed by the inventor tofurthering the art, and are to be construed as being without limitationto such specifically recited examples and conditions. Althoughembodiments of the present disclosure have been described in detail,various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the present disclosure.

What is claimed is:
 1. A wheelchair comprising: a first wheel assemblycomprising: a first exoskeleton plate with first and second portions; afirst roller guide assembly, wherein the first roller guide assemblyincludes: a first roller guide; and a first shaft spanning the first andsecond portions of the first exoskeleton plate and coupled with thefirst roller guide such that the first roller guide rotates about thefirst shaft; a first tire; and a first centerless rim coupled with thefirst tire, the first centerless rim configured to have a shape thatcorresponds to a shape of the first roller guide, wherein the firstroller guide is configured to roll along the first centerless rim as thefirst centerless rim rotates; a first drive mechanism coupled to thefirst roller guide assembly to cause the first roller guide to rotate; asecond wheel assembly comprising: a second exoskeleton plate with firstand second portions; a second roller guide assembly, wherein the secondroller guide assembly includes: a second roller guide; and a secondshaft spanning the first and second portions of the second exoskeletonplate and coupled with the second roller guide such that the secondroller guide rotates about the second shaft; a second tire; and a secondcenterless rim coupled with the second tire, the second centerless rimconfigured to have a shape that corresponds to a shape of the secondroller guide, wherein the second roller guide is configured to rollalong the second centerless rim as the second centerless rim rotates; asecond drive mechanism coupled to the second roller guide assembly tocause the second roller guide to rotate; a third wheel assembly; and apayload region.
 2. The wheelchair of claim 1, further comprising a brakeshoe coupled to the first exoskeleton plate and configured toselectively contact the first centerless rim to inhibit rotation of thefirst wheel assembly.
 3. The wheelchair of claim 1, wherein the firstdrive mechanism and the second drive mechanism are operatively coupledto operate cooperatively.
 4. The wheelchair of claim 1, wherein thefirst roller guide assembly is at a six o'clock position with respect toan inside face of the first wheel assembly and the second roller guideassembly is at a six o'clock position with respect to an inside face ofthe second wheel assembly.
 5. The wheelchair of claim 1, wherein thefirst wheel assembly includes a planetary gear coupled to the firstroller guide assembly to provide a motive force from the first drivemechanism to the first roller guide.
 6. The wheelchair of claim 5,wherein the first drive mechanism includes a lever arm coupled to aratchet mechanism coupled to the planetary gear, the ratchet mechanismconfigured to engage the lever arm with the planetary gear when rotatedin a first direction to provide a motive force to the first roller guideassembly.
 7. The wheelchair of claim 6, wherein the second wheelassembly includes a second planetary gear coupled to the second rollerguide assembly to provide a motive force from the second drive mechanismto the second roller guide; and the second drive mechanism includes asecond lever arm coupled to a second ratchet mechanism coupled to thesecond planetary gear, the second ratchet mechanism configured to engagethe second lever arm with the second planetary gear when rotated in thefirst direction to provide a motive force to the first roller guideassembly.
 8. The wheelchair of claim 6, wherein the ratchet mechanismincludes a selectable reverse feature that causes the ratchetingmechanism to operate in an opposite direction such that as the lever armis pulled in a second direction, the first roller assembly is caused torotate in an opposite direction.
 9. The wheelchair of claim 6, whereinthe first drive mechanism additionally includes a motor coupled to thefirst exoskeleton plate and includes a driven gear that couples to theplanetary gear such that the motor is configured to cause the firstroller guide to rotate.
 10. The wheelchair of claim 1, wherein the firstdrive mechanism additionally includes a motor coupled to the firstexoskeleton plate and includes a driven gear that couples to a planetarygear such that the motor is configured to cause the first roller guideto rotate.
 11. The wheelchair of claim 1, wherein the first drivemechanism includes an engine or a motor to drive the first roller guide.12. The wheelchair of claim 1, further comprising: a first horizontalstrut coupled to the first wheel assembly and the second wheel assemblyand located at approximately a seven o'clock position with respect to aninside face of the first wheel assembly, and coupled to a footboard; asecond horizontal strut coupled to the first wheel assembly and thesecond wheel assembly and located at approximately a four o'clockposition with respect to the inside face of the first wheel assembly,and coupled to the third wheel assembly; and a third horizontal strutcoupled to the first wheel assembly and the second wheel assembly andlocated at approximately a two o'clock position with respect to theinside face of the first wheel assembly, and having a seat mountedthereon.
 13. The wheelchair of claim 1, further comprising: a firsthorizontal strut; a first lockable hinge coupled to the first wheelassembly and the first horizontal strut such that a camber angle of thefirst wheel assembly may be adjusted; and a second lockable hingecoupled to the second wheel assembly and the first horizontal strut suchthat a camber angle of the second wheel assembly may be adjusted. 14.The wheelchair of claim 13, further comprising a second telescopinghorizontal strut coupled to the first wheel assembly and the secondwheel assembly and offset from the first horizontal strut.
 15. Thewheelchair of claim 13, wherein the first and the second lockable hingesare configured to rotate the first and the second wheel assembliesapproximately one hundred and twenty degrees.
 16. The wheelchair ofclaim 1, wherein the third wheel assembly includes a caster wheel. 17.The wheelchair of claim 1, further comprising a fourth wheel assembly,and wherein the first and the second wheel assemblies are approximatelythe same size and the third and the fourth wheel assemblies areapproximately the same size.
 18. The wheelchair of claim 17, wherein thethird and fourth wheel assemblies are disposed in front of the first andthe second wheel assemblies.
 19. The wheelchair of claim 17, wherein thethird and fourth wheel assemblies are disposed in back of the first andthe second wheel assemblies.
 20. The wheelchair of claim 1, wherein thefirst wheel assembly further comprises: a third roller guide assemblyshaped and positioned to roll along the first centerless rim; and afourth roller guide assembly shaped and positioned to roll along thefirst centerless rim; and a fifth roller guide assembly shaped andpositioned to limit movement of the first centerless rim to within athreshold operating region.
 21. The wheelchair of claim 20, wherein thefirst roller guide assembly is located at a six o'clock position withrespect to an inside face of the first wheel assembly; the third rollerguide assembly is located at a five o'clock position with respect to theinside face of the first wheel assembly; the fourth roller guideassembly is located at a seven o'clock position with respect to theinside face of the first wheel assembly; and the fifth roller guideassembly is located at a twelve o'clock position with respect to theinside face of the first wheel assembly.
 22. The wheelchair of claim 1,wherein at least one of the first and second exoskeleton plates aregenerally rectangular in shape.
 23. The wheelchair of claim 1, whereinthe first wheel assembly further comprises a third roller guideconfigured to operate as an anti-tipping mechanism.
 24. The wheelchairof claim 1, wherein the first and the second portions of the firstexoskeleton plate are two distinct components with a gap between them.25. The wheelchair of claim 1, further comprising a hand rail coupled tothe first exoskeleton plate.
 26. The wheelchair of claim 25, furthercomprising a control on the hand rail to activate a motor to drive thefirst roller guide assembly.
 27. A wheelchair comprising: a firstcenterless wheel assembly including a drive roller guide assembly andthree other roller guides; a first drive mechanism coupled to the firstdrive roller guide assembly to drive the first centerless wheelassembly; a second centerless wheel assembly including a second driveroller guide assembly and three additional roller guides; and a seconddrive mechanism coupled to the second drive roller guide to drive thesecond centerless wheel assembly.
 28. A wheelchair comprising: a firstcenterless wheel assembly including a drive roller guide assembly andthree other roller guides; an electric motor coupled to the first driveroller guide assembly to drive the first centerless wheel assembly; anda second centerless wheel assembly including a roller guide assembly.29. The wheelchair of claim 28, further comprising a second electricmotor coupled to the second centerless wheel assembly.
 30. Thewheelchair of claim 28, wherein the electric motor is coupled to thesecond centerless wheel assembly to drive the second centerless wheelassembly.